diff --git a/BREAKING-CHANGES-EXAMPLES.md b/BREAKING-CHANGES-EXAMPLES.md
index 9e3dbdf4..bbb644a5 100644
--- a/BREAKING-CHANGES-EXAMPLES.md
+++ b/BREAKING-CHANGES-EXAMPLES.md
@@ -168,6 +168,8 @@ These examples are automatically generated from unit tests.
 [adding an enum value to a response write-only property](checker/check-response-property-enum-value-added_test.go?plain=1#L36)  
 [adding an enum value to request parameter](checker/check-request-parameter-enum-value-updated_test.go?plain=1#L34)  
 [adding an optional write-only property to a response](checker/check-response-optional-property-updated_test.go?plain=1#L34)  
+[adding discriminator to the request body or request body property](checker/check-request-discriminator-updated_test.go?plain=1#L11)  
+[adding discriminator to the response body or response property](checker/check-response-discriminator-updated_test.go?plain=1#L11)  
 [adding pattern to request parameters](checker/check-request-parameter-pattern-added-or-changed_test.go?plain=1#L35)  
 [adding request property enum values](checker/check-request-property-enum-value-updated_test.go?plain=1#L37)  
 [adding request property pattern](checker/check-request-property-pattern-added-or-changed_test.go?plain=1#L36)  
@@ -178,6 +180,10 @@ These examples are automatically generated from unit tests.
 [changing an existing header param from required to optional](checker/checker_request_parameter_required_value_updated_test.go?plain=1#L35)  
 [changing an existing header param to optional](checker/checker_not_breaking_test.go?plain=1#L133)  
 [changing an existing request body from required to optional](checker/checker_not_breaking_test.go?plain=1#L53)  
+[changing discriminator mapping in the request body or request body property](checker/check-request-discriminator-updated_test.go?plain=1#L119)  
+[changing discriminator mapping in the response body or response property](checker/check-response-discriminator-updated_test.go?plain=1#L119)  
+[changing discriminator propertyName in the request body or request body property](checker/check-request-discriminator-updated_test.go?plain=1#L83)  
+[changing discriminator propertyName in the response body or response property](checker/check-response-discriminator-updated_test.go?plain=1#L83)  
 [changing optional request property to not read-only](checker/check-request-property-write-only-read-only_test.go?plain=1#L86)  
 [changing optional request property to not write-only](checker/check-request-property-write-only-read-only_test.go?plain=1#L36)  
 [changing optional request property to read-only](checker/check-request-property-write-only-read-only_test.go?plain=1#L61)  
@@ -220,7 +226,7 @@ These examples are automatically generated from unit tests.
 [changing required response property to optional](checker/check-response-property-became-optional_test.go?plain=1#L11)  
 [changing required response property to read-only](checker/check-response-required-property-write-only-read-only_test.go?plain=1#L63)  
 [changing required response property to write-only](checker/check-response-required-property-write-only-read-only_test.go?plain=1#L11)  
-[changing response body default value](checker/check-response-property-default-value-changed_test.go?plain=1#L33)  
+[changing response body default value](checker/check-response-property-default-value-changed_test.go?plain=1#L42)  
 [changing response body property default value](checker/check-response-property-default-value-changed_test.go?plain=1#L11)  
 [changing response property pattern](checker/check-response-pattern-added-or-changed_test.go?plain=1#L11)  
 [changing security component oauth's url](checker/check-components-security-updated_test.go?plain=1#L11)  
@@ -280,6 +286,8 @@ These examples are automatically generated from unit tests.
 [removing an existing operation id](checker/check-api-operation-id-updated_test.go?plain=1#L11)  
 [removing an existing tag](checker/check-api-tag-updated_test.go?plain=1#L36)  
 [removing an optional write-only property from a response](checker/check-response-optional-property-updated_test.go?plain=1#L11)  
+[removing discriminator from the request body or request body property](checker/check-request-discriminator-updated_test.go?plain=1#L47)  
+[removing discriminator from the response body or response property](checker/check-response-discriminator-updated_test.go?plain=1#L47)  
 [removing media type from request body](checker/check-request-body-mediatype-updated_test.go?plain=1#L34)  
 [removing pattern from request parameters](checker/check-request-parameter-pattern-added-or-changed_test.go?plain=1#L58)  
 [removing request property enum values](checker/check-request-property-enum-value-updated_test.go?plain=1#L11)  
diff --git a/checker/check-request-discriminator-updated.go b/checker/check-request-discriminator-updated.go
new file mode 100644
index 00000000..18ef0133
--- /dev/null
+++ b/checker/check-request-discriminator-updated.go
@@ -0,0 +1,148 @@
+package checker
+
+import (
+	"fmt"
+
+	"github.com/tufin/oasdiff/diff"
+)
+
+func RequestDiscriminatorUpdatedCheck(diffReport *diff.Diff, operationsSources *diff.OperationsSourcesMap, config Config) Changes {
+	result := make(Changes, 0)
+	if diffReport.PathsDiff == nil {
+		return result
+	}
+
+	for path, pathItem := range diffReport.PathsDiff.Modified {
+		if pathItem.OperationsDiff == nil {
+			continue
+		}
+
+		for operation, operationItem := range pathItem.OperationsDiff.Modified {
+			if operationItem.RequestBodyDiff == nil ||
+				operationItem.RequestBodyDiff.ContentDiff == nil ||
+				operationItem.RequestBodyDiff.ContentDiff.MediaTypeModified == nil {
+				continue
+			}
+			source := (*operationsSources)[operationItem.Revision]
+
+			appendResultItem := func(messageId string, a ...any) {
+				result = append(result, ApiChange{
+					Id:          messageId,
+					Level:       INFO,
+					Text:        fmt.Sprintf(config.i18n(messageId), a...),
+					Operation:   operation,
+					OperationId: operationItem.Revision.OperationID,
+					Path:        path,
+					Source:      source,
+				})
+			}
+
+			for _, mediaTypeDiff := range operationItem.RequestBodyDiff.ContentDiff.MediaTypeModified {
+				if mediaTypeDiff.SchemaDiff == nil {
+					continue
+				}
+
+				processDiscriminatorDiffForRequest(
+					mediaTypeDiff.SchemaDiff.DiscriminatorDiff,
+					"",
+					appendResultItem)
+
+				CheckModifiedPropertiesDiff(
+					mediaTypeDiff.SchemaDiff,
+					func(propertyPath string, propertyName string, propertyDiff *diff.SchemaDiff, parent *diff.SchemaDiff) {
+						processDiscriminatorDiffForRequest(
+							propertyDiff.DiscriminatorDiff,
+							propertyFullName(propertyPath, propertyName),
+							appendResultItem)
+					})
+
+			}
+		}
+	}
+	return result
+}
+
+func processDiscriminatorDiffForRequest(
+	discriminatorDiff *diff.DiscriminatorDiff,
+	propertyName string,
+	appendResultItem func(messageId string, a ...any)) {
+
+	if discriminatorDiff == nil {
+		return
+	}
+
+	messageIdPrefix := "request-body-discriminator"
+	if propertyName != "" {
+		messageIdPrefix = "request-property-discriminator"
+	}
+
+	if discriminatorDiff.Added {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix + "-added")
+		} else {
+			appendResultItem(messageIdPrefix+"-added", ColorizedValue(propertyName))
+		}
+		return
+	}
+	if discriminatorDiff.Deleted {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix + "-removed")
+		} else {
+			appendResultItem(messageIdPrefix+"-removed", ColorizedValue(propertyName))
+		}
+		return
+	}
+
+	if discriminatorDiff.PropertyNameDiff != nil {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix+"-property-name-changed",
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.From),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.To))
+		} else {
+			appendResultItem(messageIdPrefix+"-property-name-changed",
+				ColorizedValue(propertyName),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.From),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.To))
+		}
+	}
+
+	if discriminatorDiff.MappingDiff != nil {
+		if len(discriminatorDiff.MappingDiff.Added) > 0 {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-added",
+					ColorizedValue(discriminatorDiff.MappingDiff.Added))
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-added",
+					ColorizedValue(discriminatorDiff.MappingDiff.Added),
+					ColorizedValue(propertyName))
+			}
+		}
+
+		if len(discriminatorDiff.MappingDiff.Deleted) > 0 {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-deleted",
+					ColorizedValue(discriminatorDiff.MappingDiff.Deleted))
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-deleted",
+					ColorizedValue(discriminatorDiff.MappingDiff.Deleted),
+					ColorizedValue(propertyName))
+			}
+		}
+
+		for k, v := range discriminatorDiff.MappingDiff.Modified {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-changed",
+					ColorizedValue(k),
+					ColorizedValue(v.From),
+					ColorizedValue(v.To))
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-changed",
+					ColorizedValue(k),
+					ColorizedValue(v.From),
+					ColorizedValue(v.To),
+					ColorizedValue(propertyName))
+
+			}
+		}
+	}
+}
diff --git a/checker/check-request-discriminator-updated_test.go b/checker/check-request-discriminator-updated_test.go
new file mode 100644
index 00000000..d6f8a9b4
--- /dev/null
+++ b/checker/check-request-discriminator-updated_test.go
@@ -0,0 +1,183 @@
+package checker_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/tufin/oasdiff/checker"
+	"github.com/tufin/oasdiff/diff"
+)
+
+// CL: adding discriminator to the request body or request body property
+func TestRequestDiscriminatorUpdatedCheckAdded(t *testing.T) {
+	s1, err := open("../data/checker/request_property_discriminator_added_base.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/request_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.RequestDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "request-body-discriminator-added",
+			Text:        "added request discriminator",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_revision.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-added",
+			Text:        "added discriminator to '/oneOf[#/components/schemas/Dog]/breed' request property",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_revision.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: removing discriminator from the request body or request body property
+func TestRequestDiscriminatorUpdatedCheckRemoved(t *testing.T) {
+	s1, err := open("../data/checker/request_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/request_property_discriminator_added_base.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.RequestDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "request-body-discriminator-removed",
+			Text:        "removed request discriminator",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_base.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-removed",
+			Text:        "removed discriminator from '/oneOf[#/components/schemas/Dog]/breed' request property",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_base.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: changing discriminator propertyName in the request body or request body property
+func TestRequestDiscriminatorUpdatedCheckPropertyNameChanging(t *testing.T) {
+	s1, err := open("../data/checker/request_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/request_property_discriminator_added_property_name_changed.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.RequestDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "request-body-discriminator-property-name-changed",
+			Text:        "request discriminator property name changed from 'petType' to 'petType2'",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_property_name_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-property-name-changed",
+			Text:        "request discriminator property name changed for '/oneOf[#/components/schemas/Dog]/breed' request property from 'name' to 'name2'",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_added_property_name_changed.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: changing discriminator mapping in the request body or request body property
+func TestRequestDiscriminatorUpdatedCheckMappingChanging(t *testing.T) {
+	s1, err := open("../data/checker/request_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/request_property_discriminator_mapping_changed.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.RequestDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 5)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "request-body-discriminator-mapping-added",
+			Text:        "added '[cats]' mapping keys to the request discriminator",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-body-discriminator-mapping-deleted",
+			Text:        "removed '[cat]' mapping keys from the request discriminator",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-mapping-added",
+			Text:        "added '[breed1Code]' discriminator mapping keys to the '/oneOf[#/components/schemas/Dog]/breed' request property",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-mapping-changed",
+			Text:        "mapped value for discriminator key 'breed2' changed from '#/components/schemas/Breed2' to '#/components/schemas/Breed3' for '/oneOf[#/components/schemas/Dog]/breed' request property",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "request-property-discriminator-mapping-deleted",
+			Text:        "removed '[breed1]' discriminator mapping keys from the '/oneOf[#/components/schemas/Dog]/breed' request property",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/request_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
diff --git a/checker/check-response-discriminator-updated.go b/checker/check-response-discriminator-updated.go
new file mode 100644
index 00000000..6a3650e9
--- /dev/null
+++ b/checker/check-response-discriminator-updated.go
@@ -0,0 +1,163 @@
+package checker
+
+import (
+	"fmt"
+
+	"github.com/tufin/oasdiff/diff"
+)
+
+func ResponseDiscriminatorUpdatedCheck(diffReport *diff.Diff, operationsSources *diff.OperationsSourcesMap, config Config) Changes {
+	result := make(Changes, 0)
+	if diffReport.PathsDiff == nil {
+		return result
+	}
+
+	for path, pathItem := range diffReport.PathsDiff.Modified {
+		if pathItem.OperationsDiff == nil {
+			continue
+		}
+
+		for operation, operationItem := range pathItem.OperationsDiff.Modified {
+			if operationItem.ResponsesDiff == nil || operationItem.ResponsesDiff.Modified == nil {
+				continue
+			}
+			source := (*operationsSources)[operationItem.Revision]
+
+			appendResultItem := func(messageId string, a ...any) {
+				result = append(result, ApiChange{
+					Id:          messageId,
+					Level:       INFO,
+					Text:        fmt.Sprintf(config.i18n(messageId), a...),
+					Operation:   operation,
+					OperationId: operationItem.Revision.OperationID,
+					Path:        path,
+					Source:      source,
+				})
+			}
+
+			for responseStatus, responsesDiff := range operationItem.ResponsesDiff.Modified {
+				if responsesDiff.ContentDiff == nil || responsesDiff.ContentDiff.MediaTypeModified == nil {
+					continue
+				}
+
+				modifiedMediaTypes := responsesDiff.ContentDiff.MediaTypeModified
+				for _, mediaTypeDiff := range modifiedMediaTypes {
+					if mediaTypeDiff.SchemaDiff == nil {
+						continue
+					}
+
+					processDiscriminatorDiff(
+						mediaTypeDiff.SchemaDiff.DiscriminatorDiff,
+						responseStatus,
+						"",
+						appendResultItem)
+
+					CheckModifiedPropertiesDiff(
+						mediaTypeDiff.SchemaDiff,
+						func(propertyPath string, propertyName string, propertyDiff *diff.SchemaDiff, parent *diff.SchemaDiff) {
+							processDiscriminatorDiff(
+								propertyDiff.DiscriminatorDiff,
+								responseStatus,
+								propertyFullName(propertyPath, propertyName),
+								appendResultItem)
+						})
+				}
+			}
+		}
+	}
+	return result
+}
+
+func processDiscriminatorDiff(
+	discriminatorDiff *diff.DiscriminatorDiff,
+	responseStatus string,
+	propertyName string,
+	appendResultItem func(messageId string, a ...any)) {
+
+	if discriminatorDiff == nil {
+		return
+	}
+
+	messageIdPrefix := "response-body-discriminator"
+	if propertyName != "" {
+		messageIdPrefix = "response-property-discriminator"
+	}
+
+	if discriminatorDiff.Added {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix+"-added", responseStatus)
+		} else {
+			appendResultItem(messageIdPrefix+"-added", ColorizedValue(propertyName), responseStatus)
+		}
+		return
+	}
+	if discriminatorDiff.Deleted {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix+"-removed", responseStatus)
+		} else {
+			appendResultItem(messageIdPrefix+"-removed", ColorizedValue(propertyName), responseStatus)
+		}
+		return
+	}
+
+	if discriminatorDiff.PropertyNameDiff != nil {
+		if propertyName == "" {
+			appendResultItem(messageIdPrefix+"-property-name-changed",
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.From),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.To),
+				responseStatus)
+		} else {
+			appendResultItem(messageIdPrefix+"-property-name-changed",
+				ColorizedValue(propertyName),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.From),
+				ColorizedValue(discriminatorDiff.PropertyNameDiff.To),
+				responseStatus)
+		}
+	}
+
+	if discriminatorDiff.MappingDiff != nil {
+		if len(discriminatorDiff.MappingDiff.Added) > 0 {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-added",
+					ColorizedValue(discriminatorDiff.MappingDiff.Added),
+					responseStatus)
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-added",
+					ColorizedValue(discriminatorDiff.MappingDiff.Added),
+					ColorizedValue(propertyName),
+					responseStatus)
+			}
+		}
+
+		if len(discriminatorDiff.MappingDiff.Deleted) > 0 {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-deleted",
+					ColorizedValue(discriminatorDiff.MappingDiff.Deleted),
+					responseStatus)
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-deleted",
+					ColorizedValue(discriminatorDiff.MappingDiff.Deleted),
+					ColorizedValue(propertyName),
+					responseStatus)
+			}
+		}
+
+		for k, v := range discriminatorDiff.MappingDiff.Modified {
+			if propertyName == "" {
+				appendResultItem(messageIdPrefix+"-mapping-changed",
+					ColorizedValue(k),
+					ColorizedValue(v.From),
+					ColorizedValue(v.To),
+					responseStatus)
+			} else {
+				appendResultItem(messageIdPrefix+"-mapping-changed",
+					ColorizedValue(k),
+					ColorizedValue(v.From),
+					ColorizedValue(v.To),
+					ColorizedValue(propertyName),
+					responseStatus)
+
+			}
+		}
+	}
+}
diff --git a/checker/check-response-discriminator-updated_test.go b/checker/check-response-discriminator-updated_test.go
new file mode 100644
index 00000000..4010eba5
--- /dev/null
+++ b/checker/check-response-discriminator-updated_test.go
@@ -0,0 +1,183 @@
+package checker_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/tufin/oasdiff/checker"
+	"github.com/tufin/oasdiff/diff"
+)
+
+// CL: adding discriminator to the response body or response property
+func TestResponseDiscriminatorUpdatedCheckAdded(t *testing.T) {
+	s1, err := open("../data/checker/response_property_discriminator_added_base.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/response_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.ResponseDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "response-body-discriminator-added",
+			Text:        "added response discriminator for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_revision.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-added",
+			Text:        "added discriminator to '/oneOf[#/components/schemas/Dog]/breed' response property for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_revision.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: removing discriminator from the response body or response property
+func TestResponseDiscriminatorUpdatedCheckRemoved(t *testing.T) {
+	s1, err := open("../data/checker/response_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/response_property_discriminator_added_base.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.ResponseDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "response-body-discriminator-removed",
+			Text:        "removed response discriminator for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_base.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-removed",
+			Text:        "removed discriminator from '/oneOf[#/components/schemas/Dog]/breed' response property for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_base.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: changing discriminator propertyName in the response body or response property
+func TestResponseDiscriminatorUpdatedCheckPropertyNameChanging(t *testing.T) {
+	s1, err := open("../data/checker/response_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/response_property_discriminator_added_property_name_changed.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.ResponseDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 2)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "response-body-discriminator-property-name-changed",
+			Text:        "response discriminator property name changed from 'petType' to 'petType2' for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_property_name_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-property-name-changed",
+			Text:        "response discriminator property name changed for '/oneOf[#/components/schemas/Dog]/breed' response property from 'name' to 'name2' for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_added_property_name_changed.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
+
+// CL: changing discriminator mapping in the response body or response property
+func TestResponseDiscriminatorUpdatedCheckMappingChanging(t *testing.T) {
+	s1, err := open("../data/checker/response_property_discriminator_added_revision.yaml")
+	require.NoError(t, err)
+	s2, err := open("../data/checker/response_property_discriminator_mapping_changed.yaml")
+	require.NoError(t, err)
+
+	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
+	require.NoError(t, err)
+	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.ResponseDiscriminatorUpdatedCheck), d, osm, checker.INFO)
+
+	require.Len(t, errs, 5)
+
+	require.ElementsMatch(t, []checker.ApiChange{
+		{
+			Id:          "response-body-discriminator-mapping-added",
+			Text:        "added '[cats]' mapping keys to the response discriminator for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-body-discriminator-mapping-deleted",
+			Text:        "removed '[cat]' mapping keys from the response discriminator for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-mapping-added",
+			Text:        "added '[breed1Code]' discriminator mapping keys to the '/oneOf[#/components/schemas/Dog]/breed' response property for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-mapping-changed",
+			Text:        "mapped value for discriminator key 'breed2' changed from '#/components/schemas/Breed2' to '#/components/schemas/Breed3' for '/oneOf[#/components/schemas/Dog]/breed' response property for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		},
+		{
+			Id:          "response-property-discriminator-mapping-deleted",
+			Text:        "removed '[breed1]' discriminator mapping keys from the '/oneOf[#/components/schemas/Dog]/breed' response property for the response status 200",
+			Comment:     "",
+			Level:       checker.INFO,
+			Operation:   "POST",
+			Path:        "/pets",
+			Source:      "../data/checker/response_property_discriminator_mapping_changed.yaml",
+			OperationId: "updatePets",
+		}}, errs)
+}
diff --git a/checker/check-response-property-default-value-changed_test.go b/checker/check-response-property-default-value-changed_test.go
index 093cd87c..e0714202 100644
--- a/checker/check-response-property-default-value-changed_test.go
+++ b/checker/check-response-property-default-value-changed_test.go
@@ -17,8 +17,8 @@ func TestResponsePropertyDefaultValueUpdatedCheck(t *testing.T) {
 	d, osm, err := diff.GetWithOperationsSourcesMap(getConfig(), s1, s2)
 	require.NoError(t, err)
 	errs := checker.CheckBackwardCompatibilityUntilLevel(singleCheckConfig(checker.ResponsePropertyDefaultValueChangedCheck), d, osm, checker.INFO)
-	require.Len(t, errs, 1)
-	require.Equal(t, checker.ApiChange{
+	require.Len(t, errs, 2)
+	require.ElementsMatch(t, []checker.ApiChange{{
 		Id:          "response-property-default-value-changed",
 		Text:        "the 'created' response's property default value changed from '2020-01-01T00:00:00Z' to '2020-02-01T00:00:00Z' for the status '200'",
 		Comment:     "",
@@ -27,7 +27,16 @@ func TestResponsePropertyDefaultValueUpdatedCheck(t *testing.T) {
 		Path:        "/api/v1.0/groups",
 		Source:      "../data/checker/response_property_default_value_changed_revision.yaml",
 		OperationId: "createOneGroup",
-	}, errs[0])
+	}, {
+		Id:          "response-property-default-value-changed",
+		Text:        "the 'enabled' response's property default value changed from 'false' to 'true' for the status '200'",
+		Comment:     "",
+		Level:       checker.INFO,
+		Operation:   "POST",
+		Path:        "/api/v1.0/groups",
+		Source:      "../data/checker/response_property_default_value_changed_revision.yaml",
+		OperationId: "createOneGroup",
+	}}, errs)
 }
 
 // CL: changing response body default value
diff --git a/checker/checks-utils.go b/checker/checks-utils.go
index b7b03ba5..87f7d580 100644
--- a/checker/checks-utils.go
+++ b/checker/checks-utils.go
@@ -30,22 +30,23 @@ func interfaceToString(arg interface{}) string {
 		return "undefined"
 	}
 
-	argString, ok := arg.(string)
-	if ok {
+	if argString, ok := arg.(string); ok {
 		return argString
 	}
 
-	argUint64, ok := arg.(uint64)
-	if ok {
+	if argUint64, ok := arg.(uint64); ok {
 		return fmt.Sprintf("%d", argUint64)
 	}
 
-	argFloat64, ok := arg.(float64)
-	if ok {
+	if argFloat64, ok := arg.(float64); ok {
 		return fmt.Sprintf("%.2f", argFloat64)
 	}
 
-	return fmt.Sprintf("%s", arg)
+	if argBool, ok := arg.(bool); ok {
+		return fmt.Sprintf("%t", argBool)
+	}
+
+	return fmt.Sprintf("%v", arg)
 }
 
 func CheckModifiedPropertiesDiff(schemaDiff *diff.SchemaDiff, processor func(propertyPath string, propertyName string, propertyItem *diff.SchemaDiff, propertyParentItem *diff.SchemaDiff)) {
diff --git a/checker/default_checks.go b/checker/default_checks.go
index f0e42ebb..4923ed30 100644
--- a/checker/default_checks.go
+++ b/checker/default_checks.go
@@ -137,6 +137,8 @@ func defaultChecks() []BackwardCompatibilityCheck {
 		RequestPropertyAllOfUpdated,
 		ResponsePropertyAllOfUpdated,
 		RequestPropertyWriteOnlyReadOnlyCheck,
+		RequestDiscriminatorUpdatedCheck,
+		ResponseDiscriminatorUpdatedCheck,
 	}
 }
 
diff --git a/checker/localizations/localizations.go b/checker/localizations/localizations.go
index 7d6cb22b..644a2d0e 100644
--- a/checker/localizations/localizations.go
+++ b/checker/localizations/localizations.go
@@ -1,6 +1,6 @@
 // Code generated by go-localize; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-31 22:54:08.00252 +0100 IST m=+0.005108876
+// 2023-08-03 13:39:56.106803 +0100 IST m=+0.005883043
 
 package localizations
 
@@ -66,6 +66,12 @@ var localizations = map[string]string{
 	"en.messages.request-body-became-optional":                             "request body became optional",
 	"en.messages.request-body-became-required":                             "request body became required",
 	"en.messages.request-body-default-value-changed":                       "the request body %s default value changed from %s to %s",
+	"en.messages.request-body-discriminator-added":                         "added request discriminator",
+	"en.messages.request-body-discriminator-mapping-added":                 "added %s mapping keys to the request discriminator",
+	"en.messages.request-body-discriminator-mapping-changed":               "mapped value for key %s changed from %s to %s from the request discriminator",
+	"en.messages.request-body-discriminator-mapping-deleted":               "removed %s mapping keys from the request discriminator",
+	"en.messages.request-body-discriminator-property-name-changed":         "request discriminator property name changed from %s to %s",
+	"en.messages.request-body-discriminator-removed":                       "removed request discriminator",
 	"en.messages.request-body-enum-value-removed":                          "request body enum value removed %s",
 	"en.messages.request-body-max-decreased":                               "the request's body max was decreased to %s",
 	"en.messages.request-body-max-increased":                               "the request's body max was increased from %s to %s",
@@ -138,6 +144,12 @@ var localizations = map[string]string{
 	"en.messages.request-property-became-optional":                         "the request property %s became optional",
 	"en.messages.request-property-became-required":                         "the request property %s became required",
 	"en.messages.request-property-default-value-changed":                   "the %s request property default value changed from %s to %s",
+	"en.messages.request-property-discriminator-added":                     "added discriminator to %s request property",
+	"en.messages.request-property-discriminator-mapping-added":             "added %s discriminator mapping keys to the %s request property",
+	"en.messages.request-property-discriminator-mapping-changed":           "mapped value for discriminator key %s changed from %s to %s for %s request property",
+	"en.messages.request-property-discriminator-mapping-deleted":           "removed %s discriminator mapping keys from the %s request property",
+	"en.messages.request-property-discriminator-property-name-changed":     "request discriminator property name changed for %s request property from %s to %s",
+	"en.messages.request-property-discriminator-removed":                   "removed discriminator from %s request property",
 	"en.messages.request-property-enum-value-added":                        "added the new %s enum value to the request property %s",
 	"en.messages.request-property-enum-value-removed":                      "removed the enum value %s of the request property %s",
 	"en.messages.request-property-max-decreased":                           "the %s request property's max was decreased to %s",
@@ -177,6 +189,12 @@ var localizations = map[string]string{
 	"en.messages.response-body-any-of-removed":                             "removed %s from the response body 'anyOf' list for the response status %s",
 	"en.messages.response-body-became-nullable":                            "the response's body became nullable",
 	"en.messages.response-body-default-value-changed":                      "the response body %s default value changed from %s to %s for the status %s",
+	"en.messages.response-body-discriminator-added":                        "added response discriminator for the response status %s",
+	"en.messages.response-body-discriminator-mapping-added":                "added %s mapping keys to the response discriminator for the response status %s",
+	"en.messages.response-body-discriminator-mapping-changed":              "mapped value for key %s changed from %s to %s from the response discriminator for the response status %s",
+	"en.messages.response-body-discriminator-mapping-deleted":              "removed %s mapping keys from the response discriminator for the response status %s",
+	"en.messages.response-body-discriminator-property-name-changed":        "response discriminator property name changed from %s to %s for the response status %s",
+	"en.messages.response-body-discriminator-removed":                      "removed response discriminator for the response status %s",
 	"en.messages.response-body-max-increased":                              "the response's body max was increased from %s to %s",
 	"en.messages.response-body-max-length-increased":                       "the response's body maxLength was increased from %s to %s",
 	"en.messages.response-body-max-length-unset":                           "the response's body maxLength was unset from %s",
@@ -209,6 +227,12 @@ var localizations = map[string]string{
 	"en.messages.response-property-became-optional":                        "the response property %s became optional for the status %s",
 	"en.messages.response-property-became-required":                        "the response property %s became required for the status %s",
 	"en.messages.response-property-default-value-changed":                  "the %s response's property default value changed from %s to %s for the status %s",
+	"en.messages.response-property-discriminator-added":                    "added discriminator to %s response property for the response status %s",
+	"en.messages.response-property-discriminator-mapping-added":            "added %s discriminator mapping keys to the %s response property for the response status %s",
+	"en.messages.response-property-discriminator-mapping-changed":          "mapped value for discriminator key %s changed from %s to %s for %s response property for the response status %s",
+	"en.messages.response-property-discriminator-mapping-deleted":          "removed %s discriminator mapping keys from the %s response property for the response status %s",
+	"en.messages.response-property-discriminator-property-name-changed":    "response discriminator property name changed for %s response property from %s to %s for the response status %s",
+	"en.messages.response-property-discriminator-removed":                  "removed discriminator from %s response property for the response status %s",
 	"en.messages.response-property-enum-value-added":                       "added the new '%s' enum value to the %s response property for the response status %s",
 	"en.messages.response-property-enum-value-added-comment":               "Adding new enum values to response could be unexpected for clients, use x-extensible-enum instead.",
 	"en.messages.response-property-enum-value-removed":                     "removed the '%s' enum value from the %s response property for the response status %s",
@@ -296,6 +320,12 @@ var localizations = map[string]string{
 	"ru.messages.request-body-became-optional":                             "тело запроса стало необязательным",
 	"ru.messages.request-body-became-required":                             "тело запроса стало обязательным",
 	"ru.messages.request-body-default-value-changed":                       "значение по умолчанию для тела запроса было изменено с %s на %s",
+	"ru.messages.request-body-discriminator-added":                         "добавлен дискриминатор запроса",
+	"ru.messages.request-body-discriminator-mapping-added":                 "добавлены ключи сопоставления %s для дискриминатора запроса",
+	"ru.messages.request-body-discriminator-mapping-changed":               "значение для ключа %s изменено с %s на %s в дискриминаторе запроса",
+	"ru.messages.request-body-discriminator-mapping-deleted":               "удалены ключи сопоставления %s из дискриминатора запроса",
+	"ru.messages.request-body-discriminator-property-name-changed":         "имя свойства дискриминатора запроса изменено с %s на %s",
+	"ru.messages.request-body-discriminator-removed":                       "удален дискриминатор запроса",
 	"ru.messages.request-body-enum-value-removed":                          "значение перечисления тела запроса удалено %s",
 	"ru.messages.request-body-max-decreased":                               "значение max у тела запроса уменьшено до %s",
 	"ru.messages.request-body-max-increased":                               "максимум тела запроса был увеличен с %s до %s",
@@ -368,6 +398,12 @@ var localizations = map[string]string{
 	"ru.messages.request-property-became-optional":                         "поле запроса %s стало необязательным",
 	"ru.messages.request-property-became-required":                         "поле запроса %s стало обязательным",
 	"ru.messages.request-property-default-value-changed":                   "значение по умолчанию для свойства %s в запросе было изменено с %s на %s",
+	"ru.messages.request-property-discriminator-added":                     "добавлен дискриминатор к свойству запроса %s",
+	"ru.messages.request-property-discriminator-mapping-added":             "добавлены ключи сопоставления дискриминатора %s для свойства запроса %s",
+	"ru.messages.request-property-discriminator-mapping-changed":           "значение для ключа дискриминатора %s изменено с %s на %s для свойства запроса %s",
+	"ru.messages.request-property-discriminator-mapping-deleted":           "удалены ключи сопоставления дискриминатора %s из свойства запроса %s",
+	"ru.messages.request-property-discriminator-property-name-changed":     "имя свойства дискриминатора запроса изменено для свойства запроса %s с %s на %s",
+	"ru.messages.request-property-discriminator-removed":                   "удален дискриминатор из свойства запроса %s",
 	"ru.messages.request-property-enum-value-added":                        "добавлено enum значение %s у поля запроса %s",
 	"ru.messages.request-property-enum-value-removed":                      "удалено enum значение %s у поля запроса %s",
 	"ru.messages.request-property-max-decreased":                           "значение max у поля запроса %s уменьшено до %s",
@@ -407,6 +443,12 @@ var localizations = map[string]string{
 	"ru.messages.response-body-any-of-removed":                             "удалён %s из списка 'anyOf' тела ответа для статуса ответа %s",
 	"ru.messages.response-body-became-nullable":                            "у тела ответа стало обнуляемым",
 	"ru.messages.response-body-default-value-changed":                      "значение по умолчанию для тела ответа со статусом %s было изменено с %s на %s",
+	"ru.messages.response-body-discriminator-added":                        "добавлен дискриминатор ответа для статуса ответа %s",
+	"ru.messages.response-body-discriminator-mapping-added":                "добавлены ключи сопоставления %s для дискриминатора ответа для статуса ответа %s",
+	"ru.messages.response-body-discriminator-mapping-changed":              "значение для ключа %s изменено с %s на %s в дискриминаторе ответа для статуса ответа %s",
+	"ru.messages.response-body-discriminator-mapping-deleted":              "удалены ключи сопоставления %s из дискриминатора ответа для статуса ответа %s",
+	"ru.messages.response-body-discriminator-property-name-changed":        "имя свойства дискриминатора ответа изменено с %s на %s для статуса ответа %s",
+	"ru.messages.response-body-discriminator-removed":                      "удален дискриминатор ответа для статуса ответа %s",
 	"ru.messages.response-body-max-increased":                              "у тела ответа max увеличен с %s до %s",
 	"ru.messages.response-body-max-length-increased":                       "у тела ответа maxLength увеличен с %s до %s",
 	"ru.messages.response-body-max-length-unset":                           "у тела ответа maxLength был удалён, предыдущее значение - %s",
@@ -440,6 +482,12 @@ var localizations = map[string]string{
 	"ru.messages.response-property-became-required":                        "свойство %s перестало быть необязательным для ответа со статусом %s",
 	"ru.messages.response-property-became-write-only":                      "свойство %s перестало быть только для записи для ответа со статусом %s",
 	"ru.messages.response-property-default-value-changed":                  "значение по умолчанию для свойства %s в ответе со статусом %s было изменено с %s на %s",
+	"ru.messages.response-property-discriminator-added":                    "добавлен дискриминатор к свойству ответа %s для статуса ответа %s",
+	"ru.messages.response-property-discriminator-mapping-added":            "добавлены ключи сопоставления дискриминатора %s для свойства ответа %s для статуса ответа %s",
+	"ru.messages.response-property-discriminator-mapping-changed":          "значение для ключа дискриминатора %s изменено с %s на %s для свойства ответа %s для статуса ответа %s",
+	"ru.messages.response-property-discriminator-mapping-deleted":          "удалены ключи сопоставления дискриминатора %s из свойства ответа %s для статуса ответа %s",
+	"ru.messages.response-property-discriminator-property-name-changed":    "имя свойства дискриминатора ответа изменено для свойства ответа %s с %s на %s для статуса ответа %s",
+	"ru.messages.response-property-discriminator-removed":                  "удален дискриминатор из свойства ответа %s для статуса ответа %s",
 	"ru.messages.response-property-enum-value-added":                       "добавлено новое enum значение %s в поле ответа %s для ответа со статусом %s",
 	"ru.messages.response-property-enum-value-added-comment":               "Добавление новых значений перечисления в ответ может быть неожиданным для клиентов, вместо этого используйте x-extensible-enum.",
 	"ru.messages.response-property-enum-value-removed":                     "удалено значение перечисления '%s' из свойства ответа %s для статуса ответа %s.",
diff --git a/checker/localizations_src/en/messages.yaml b/checker/localizations_src/en/messages.yaml
index 2cff6b87..8656b5bd 100644
--- a/checker/localizations_src/en/messages.yaml
+++ b/checker/localizations_src/en/messages.yaml
@@ -220,11 +220,35 @@ response-body-all-of-added: added %s to the response body 'allOf' list for the r
 response-body-all-of-removed: removed %s from the response body 'allOf' list for the response status %s
 response-property-all-of-added: added %s to the %s response property 'allOf' list for the response status %s
 response-property-all-of-removed: removed %s from the %s response property 'allOf' list for the response status %s
-request-required-property-became-read-only: the request required property %s became read-only 
+response-body-discriminator-added: added response discriminator for the response status %s
+response-property-discriminator-added: added discriminator to %s response property for the response status %s
+response-body-discriminator-removed: removed response discriminator for the response status %s
+response-property-discriminator-removed: removed discriminator from %s response property for the response status %s
+response-body-discriminator-property-name-changed: response discriminator property name changed from %s to %s for the response status %s
+response-property-discriminator-property-name-changed: response discriminator property name changed for %s response property from %s to %s for the response status %s
+response-body-discriminator-mapping-added: added %s mapping keys to the response discriminator for the response status %s
+response-property-discriminator-mapping-added: added %s discriminator mapping keys to the %s response property for the response status %s
+response-body-discriminator-mapping-deleted: removed %s mapping keys from the response discriminator for the response status %s
+response-property-discriminator-mapping-deleted: removed %s discriminator mapping keys from the %s response property for the response status %s
+response-body-discriminator-mapping-changed: mapped value for key %s changed from %s to %s from the response discriminator for the response status %s
+response-property-discriminator-mapping-changed: mapped value for discriminator key %s changed from %s to %s for %s response property for the response status %s
+request-body-discriminator-added: added request discriminator
+request-property-discriminator-added: added discriminator to %s request property
+request-body-discriminator-removed: removed request discriminator
+request-property-discriminator-removed: removed discriminator from %s request property
+request-body-discriminator-property-name-changed: request discriminator property name changed from %s to %s
+request-property-discriminator-property-name-changed: request discriminator property name changed for %s request property from %s to %s
+request-body-discriminator-mapping-added: added %s mapping keys to the request discriminator
+request-property-discriminator-mapping-added: added %s discriminator mapping keys to the %s request property
+request-body-discriminator-mapping-deleted: removed %s mapping keys from the request discriminator
+request-property-discriminator-mapping-deleted: removed %s discriminator mapping keys from the %s request property
+request-body-discriminator-mapping-changed: mapped value for key %s changed from %s to %s from the request discriminator
+request-property-discriminator-mapping-changed: mapped value for discriminator key %s changed from %s to %s for %s request property
+request-required-property-became-read-only: the request required property %s became read-only
 request-required-property-became-not-read-only: the request required property %s became not read-only
 request-optional-property-became-write-only: the request optional property %s became write-only
 request-optional-property-became-read-only: the request optional property %s became read-only
 request-optional-property-became-not-write-only: the request optional property %s became not write-only
 request-optional-property-became-not-read-only: the request optional property %s became not read-only
 request-required-property-became-write-only: the request required property %s became write-only
-request-required-property-became-not-write-only: the request required property %s became not write-only
\ No newline at end of file
+request-required-property-became-not-write-only: the request required property %s became not write-only
diff --git a/checker/localizations_src/ru/messages.yaml b/checker/localizations_src/ru/messages.yaml
index 815ef349..fc08ebae 100644
--- a/checker/localizations_src/ru/messages.yaml
+++ b/checker/localizations_src/ru/messages.yaml
@@ -218,6 +218,30 @@ response-body-all-of-added: добавлено %s в список 'allOf' тел
 response-body-all-of-removed: удалён %s из списка 'allOf' тела ответа для статуса ответа %s
 response-property-all-of-added: добавлено %s в список 'allOf' свойства ответа %s для статуса ответа %s
 response-property-all-of-removed: удалён %s из списка 'allOf' свойства ответа %s для статуса ответа %s
+response-body-discriminator-added: добавлен дискриминатор ответа для статуса ответа %s
+response-property-discriminator-added: добавлен дискриминатор к свойству ответа %s для статуса ответа %s
+response-body-discriminator-removed: удален дискриминатор ответа для статуса ответа %s
+response-property-discriminator-removed: удален дискриминатор из свойства ответа %s для статуса ответа %s
+response-body-discriminator-property-name-changed: имя свойства дискриминатора ответа изменено с %s на %s для статуса ответа %s
+response-property-discriminator-property-name-changed: имя свойства дискриминатора ответа изменено для свойства ответа %s с %s на %s для статуса ответа %s
+response-body-discriminator-mapping-added: добавлены ключи сопоставления %s для дискриминатора ответа для статуса ответа %s
+response-property-discriminator-mapping-added: добавлены ключи сопоставления дискриминатора %s для свойства ответа %s для статуса ответа %s
+response-body-discriminator-mapping-deleted: удалены ключи сопоставления %s из дискриминатора ответа для статуса ответа %s
+response-property-discriminator-mapping-deleted: удалены ключи сопоставления дискриминатора %s из свойства ответа %s для статуса ответа %s
+response-body-discriminator-mapping-changed: значение для ключа %s изменено с %s на %s в дискриминаторе ответа для статуса ответа %s
+response-property-discriminator-mapping-changed: значение для ключа дискриминатора %s изменено с %s на %s для свойства ответа %s для статуса ответа %s
+request-body-discriminator-added: добавлен дискриминатор запроса
+request-property-discriminator-added: добавлен дискриминатор к свойству запроса %s
+request-body-discriminator-removed: удален дискриминатор запроса
+request-property-discriminator-removed: удален дискриминатор из свойства запроса %s
+request-body-discriminator-property-name-changed: имя свойства дискриминатора запроса изменено с %s на %s
+request-property-discriminator-property-name-changed: имя свойства дискриминатора запроса изменено для свойства запроса %s с %s на %s
+request-body-discriminator-mapping-added: добавлены ключи сопоставления %s для дискриминатора запроса
+request-property-discriminator-mapping-added: добавлены ключи сопоставления дискриминатора %s для свойства запроса %s
+request-body-discriminator-mapping-deleted: удалены ключи сопоставления %s из дискриминатора запроса
+request-property-discriminator-mapping-deleted: удалены ключи сопоставления дискриминатора %s из свойства запроса %s
+request-body-discriminator-mapping-changed: значение для ключа %s изменено с %s на %s в дискриминаторе запроса
+request-property-discriminator-mapping-changed: значение для ключа дискриминатора %s изменено с %s на %s для свойства запроса %s
 request-property-default-value-changed: значение по умолчанию для свойства %s в запросе было изменено с %s на %s 
 request-body-default-value-changed: значение по умолчанию для тела запроса было изменено с %s на %s
 request-required-property-became-read-only: обязательное поле запроса %s стало только для чтения
@@ -227,4 +251,4 @@ request-optional-property-became-read-only: необязательное пол
 request-optional-property-became-not-write-only: необязательное поле запроса %s перестало быть только для записи
 request-optional-property-became-not-read-only: необязательное поле запроса %s перестало быть только для чтения
 request-required-property-became-write-only: обязательное поле запроса %s стало только для записи
-request-required-property-became-not-write-only: обязательное поле запроса %s перестало быть только для записи
\ No newline at end of file
+request-required-property-became-not-write-only: обязательное поле запроса %s перестало быть только для записи
diff --git a/data/checker/request_property_discriminator_added_base.yaml b/data/checker/request_property_discriminator_added_base.yaml
new file mode 100644
index 00000000..8a880a8e
--- /dev/null
+++ b/data/checker/request_property_discriminator_added_base.yaml
@@ -0,0 +1,51 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      requestBody:
+        content:
+          application/json:
+            schema:
+              oneOf:
+                - $ref: "#/components/schemas/Dog"
+                - $ref: "#/components/schemas/Cat"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/request_property_discriminator_added_property_name_changed.yaml b/data/checker/request_property_discriminator_added_property_name_changed.yaml
new file mode 100644
index 00000000..c342174e
--- /dev/null
+++ b/data/checker/request_property_discriminator_added_property_name_changed.yaml
@@ -0,0 +1,61 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      requestBody:
+        content:
+          application/json:
+            schema:
+              oneOf:
+                - $ref: "#/components/schemas/Dog"
+                - $ref: "#/components/schemas/Cat"
+              discriminator:
+                propertyName: petType2
+                mapping:
+                  cat: "#/components/schemas/Cat"
+                  dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType2:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name2
+            mapping:
+              breed1: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name2:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name2:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType2:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/request_property_discriminator_added_revision.yaml b/data/checker/request_property_discriminator_added_revision.yaml
new file mode 100644
index 00000000..674d0c9e
--- /dev/null
+++ b/data/checker/request_property_discriminator_added_revision.yaml
@@ -0,0 +1,61 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      requestBody:
+        content:
+          application/json:
+            schema:
+              oneOf:
+                - $ref: "#/components/schemas/Dog"
+                - $ref: "#/components/schemas/Cat"
+              discriminator:
+                propertyName: petType
+                mapping:
+                  cat: "#/components/schemas/Cat"
+                  dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name
+            mapping:
+              breed1: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/request_property_discriminator_mapping_changed.yaml b/data/checker/request_property_discriminator_mapping_changed.yaml
new file mode 100644
index 00000000..cb5051a3
--- /dev/null
+++ b/data/checker/request_property_discriminator_mapping_changed.yaml
@@ -0,0 +1,67 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      requestBody:
+        content:
+          application/json:
+            schema:
+              oneOf:
+                - $ref: "#/components/schemas/Dog"
+                - $ref: "#/components/schemas/Cat"
+              discriminator:
+                propertyName: petType
+                mapping:
+                  cats: "#/components/schemas/Cat"
+                  dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name
+            mapping:
+              breed1Code: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed3"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed3:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/response_property_default_value_changed_base.yaml b/data/checker/response_property_default_value_changed_base.yaml
index 77515be2..60ad88a5 100644
--- a/data/checker/response_property_default_value_changed_base.yaml
+++ b/data/checker/response_property_default_value_changed_base.yaml
@@ -3,7 +3,7 @@ info:
   title: Tufin
   version: "2.0"
 servers:
-- url: https://localhost:9080
+  - url: https://localhost:9080
 paths:
   /api/v1.0/groups:
     post:
@@ -13,7 +13,7 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/GroupView'
+                $ref: "#/components/schemas/GroupView"
           description: OK
         "404":
           content:
@@ -21,7 +21,7 @@ paths:
               schema:
                 type: string
                 default: "Error"
-          description: Error   
+          description: Error
       summary: Create One Project
 components:
   parameters:
@@ -49,5 +49,8 @@ components:
               readOnly: true
             name:
               type: string
+            enabled:
+              default: false
+              type: boolean
           required:
-            - name
\ No newline at end of file
+            - name
diff --git a/data/checker/response_property_default_value_changed_revision.yaml b/data/checker/response_property_default_value_changed_revision.yaml
index 949ed242..3e10bf36 100644
--- a/data/checker/response_property_default_value_changed_revision.yaml
+++ b/data/checker/response_property_default_value_changed_revision.yaml
@@ -3,7 +3,7 @@ info:
   title: Tufin
   version: "2.0"
 servers:
-- url: https://localhost:9080
+  - url: https://localhost:9080
 paths:
   /api/v1.0/groups:
     post:
@@ -13,7 +13,7 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/GroupView'
+                $ref: "#/components/schemas/GroupView"
           description: OK
         "404":
           content:
@@ -21,7 +21,7 @@ paths:
               schema:
                 type: string
                 default: "Error"
-          description: Error   
+          description: Error
       summary: Create One Project
 components:
   parameters:
@@ -49,5 +49,8 @@ components:
               readOnly: true
             name:
               type: string
+            enabled:
+              default: true
+              type: boolean
           required:
-            - name
\ No newline at end of file
+            - name
diff --git a/data/checker/response_property_discriminator_added_base.yaml b/data/checker/response_property_discriminator_added_base.yaml
new file mode 100644
index 00000000..8fcc380b
--- /dev/null
+++ b/data/checker/response_property_discriminator_added_base.yaml
@@ -0,0 +1,52 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/Dog"
+                  - $ref: "#/components/schemas/Cat"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/response_property_discriminator_added_property_name_changed.yaml b/data/checker/response_property_discriminator_added_property_name_changed.yaml
new file mode 100644
index 00000000..3794c87f
--- /dev/null
+++ b/data/checker/response_property_discriminator_added_property_name_changed.yaml
@@ -0,0 +1,62 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/Dog"
+                  - $ref: "#/components/schemas/Cat"
+                discriminator:
+                  propertyName: petType2
+                  mapping:
+                    cat: "#/components/schemas/Cat"
+                    dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType2:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name2
+            mapping:
+              breed1: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name2:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name2:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType2:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/response_property_discriminator_added_revision.yaml b/data/checker/response_property_discriminator_added_revision.yaml
new file mode 100644
index 00000000..b40b50ab
--- /dev/null
+++ b/data/checker/response_property_discriminator_added_revision.yaml
@@ -0,0 +1,62 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/Dog"
+                  - $ref: "#/components/schemas/Cat"
+                discriminator:
+                  propertyName: petType
+                  mapping:
+                    cat: "#/components/schemas/Cat"
+                    dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name
+            mapping:
+              breed1: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed2"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
diff --git a/data/checker/response_property_discriminator_mapping_changed.yaml b/data/checker/response_property_discriminator_mapping_changed.yaml
new file mode 100644
index 00000000..c3883217
--- /dev/null
+++ b/data/checker/response_property_discriminator_mapping_changed.yaml
@@ -0,0 +1,68 @@
+openapi: 3.0.0
+info:
+  title: ACME
+  version: 1.0.0
+
+paths:
+  /pets:
+    post:
+      operationId: updatePets
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/Dog"
+                  - $ref: "#/components/schemas/Cat"
+                discriminator:
+                  propertyName: petType
+                  mapping:
+                    cats: "#/components/schemas/Cat"
+                    dog: "#/components/schemas/Dog"
+
+components:
+  schemas:
+    Dog:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+        breed:
+          type: object
+          oneOf:
+            - $ref: "#/components/schemas/Breed1"
+            - $ref: "#/components/schemas/Breed2"
+          discriminator:
+            propertyName: name
+            mapping:
+              breed1Code: "#/components/schemas/Breed1"
+              breed2: "#/components/schemas/Breed3"
+
+    Breed1:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed2:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Breed3:
+      type: object
+      properties:
+        name:
+          type: string
+
+    Cat:
+      type: object
+      properties:
+        petType:
+          type: string
+        name:
+          type: string