diff --git a/Sources/Spyder/API+Invoking.swift b/Sources/Spyder/API+Invoking.swift
index 66d0a32..ab426ae 100644
--- a/Sources/Spyder/API+Invoking.swift
+++ b/Sources/Spyder/API+Invoking.swift
@@ -1,4 +1,7 @@
 import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
 
 // MARK: API invoking functions
 
@@ -6,6 +9,7 @@ extension API {
   public func invokeAndForget<Input>(request: Input) async throws
   where Input: URLRequestBuilder {
     let urlRequest = try request.urlRequest(for: self)
+    logInvoke(for: urlRequest)
     do {
       let response = try await invoker(urlRequest)
       logResponse(for: urlRequest, response: response)
@@ -17,6 +21,7 @@ extension API {
   public func invokeWaitingResponse<Input, Output>(request: Input) async throws -> Output
   where Input: URLRequestBuilder, Output: Decodable {
     let urlRequest = try request.urlRequest(for: self)
+    logInvoke(for: urlRequest)
     let response: HTTPResponse = try await {
       do {
         var response = try await invoker(urlRequest)
@@ -47,7 +52,17 @@ public enum Invoker {
     guard let httpResponse = response as? HTTPURLResponse else {
       throw Invoker.DefaultHTTPInvokerError.missingHTTPResponse
     }
-    return .init(statusCode: httpResponse.statusCode, data: data)
+    return .init(
+      statusCode: httpResponse.statusCode,
+      headers: httpResponse.allHeaderFields.compactMap { element in
+        guard
+          let stringKey = element.key as? String,
+          let value = element.value as? String
+        else { return .none }
+        return .init(name: stringKey, value: value)
+      },
+      data: data
+    )
   }
 }
 extension Invoker {
diff --git a/Sources/Spyder/API+Logging.swift b/Sources/Spyder/API+Logging.swift
index cb0648b..62d2091 100644
--- a/Sources/Spyder/API+Logging.swift
+++ b/Sources/Spyder/API+Logging.swift
@@ -1,6 +1,20 @@
 import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
 
 extension API {
+  internal func logInvoke(for urlRequest: URLRequest) {
+    logger(
+      "🕸️ invoke",
+      [
+        "method=[\(urlRequest.httpMethod ?? "GET")]",
+        "absolute_url=[\(urlRequest.url?.absoluteString ?? "nil")]",
+        "headers=[\(urlRequest.allHTTPHeaderFields ?? [:])]",
+        "body=[\(urlRequest.httpBody?.jsonString(options: .prettyPrinted) ?? "nil")]"
+      ].joined(separator: ", ")
+    )
+  }
   internal func logResponse(for urlRequest: URLRequest, response: HTTPResponse) {
     let isSuccess = (200...299).contains(response.statusCode)
     logNetworkingEvent(
@@ -40,3 +54,16 @@ extension API {
     logger(message, complementary)
   }
 }
+
+private extension Data {
+  func jsonString(options: JSONSerialization.WritingOptions = []) -> String? {
+    guard
+      let object = try? JSONSerialization.jsonObject(with: self, options: []),
+      let data = try? JSONSerialization.data(withJSONObject: object, options: options),
+      let jsonString = String(data: data, encoding: .utf8)
+    else {
+      return nil
+    }
+    return jsonString
+  }
+}
diff --git a/Sources/Spyder/API+Public.swift b/Sources/Spyder/API+Public.swift
new file mode 100644
index 0000000..62e1006
--- /dev/null
+++ b/Sources/Spyder/API+Public.swift
@@ -0,0 +1,10 @@
+extension API {
+  public func addHeader(_ header: Header) {
+    persistentHeaders.insert(header)
+  }
+  public var allHeaders: Set<Header> {
+    var dynamicHeaders = headersBuilder()
+    persistentHeaders.forEach { dynamicHeaders.insert($0) }
+    return dynamicHeaders
+  }
+}
diff --git a/Sources/Spyder/API+Types.swift b/Sources/Spyder/API+Types.swift
index ba19225..794d3f9 100644
--- a/Sources/Spyder/API+Types.swift
+++ b/Sources/Spyder/API+Types.swift
@@ -6,17 +6,19 @@ public enum HTTPMethod: String {
 
 public struct HTTPResponse {
   public let statusCode: Int
+  public let headers: [Header]
   public let data: Data
 
-  public init(statusCode: Int, data: Data) {
+  public init(statusCode: Int, headers: [Header], data: Data) {
     self.statusCode = statusCode
+    self.headers = headers
     self.data = data
   }
 }
 
 public struct Header: Hashable {
-  let name: String
-  let value: String
+  public let name: String
+  public let value: String
 
   public init(name: String, value: String) {
     self.name = name
@@ -24,6 +26,12 @@ public struct Header: Hashable {
   }
 }
 
+extension Header {
+  public static func authorization(bearer value: String) -> Self {
+    .init(name: "Authorization", value: "Bearer \(value)")
+  }
+}
+
 extension Header {
   public enum ContentType: String {
     case image = "image/jpeg"
@@ -32,9 +40,6 @@ extension Header {
   }
 
   public static func contentType(_ value: Header.ContentType) -> Self {
-    .init(
-      name: "Content-Type",
-      value: value.rawValue
-    )
+    .init(name: "Content-Type", value: value.rawValue)
   }
 }
diff --git a/Sources/Spyder/API.swift b/Sources/Spyder/API.swift
index b3c68ad..8ea46c1 100644
--- a/Sources/Spyder/API.swift
+++ b/Sources/Spyder/API.swift
@@ -1,6 +1,9 @@
 import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
 
-public struct API<ConstrainedType> {
+public class API<ConstrainedType> {
   public typealias HeadersBuilder = () -> Set<Header>
   public typealias Invoker = (URLRequest) async throws -> HTTPResponse
   public typealias Logger = (_ message: String, _ complementaryMessage: String) -> Void
@@ -10,6 +13,7 @@ public struct API<ConstrainedType> {
   public let jsonEncoder: JSONEncoder
   public let jsonDecoder: JSONDecoder
   let headersBuilder: HeadersBuilder
+  var persistentHeaders: Set<Header>
   let invoker: Invoker
   let logger: Logger
   let responseMiddlewares: [ResponseMiddleware]
@@ -19,6 +23,7 @@ public struct API<ConstrainedType> {
     jsonEncoder: JSONEncoder = .init(),
     jsonDecoder: JSONDecoder = .init(),
     headersBuilder: @escaping HeadersBuilder = { .init() },
+    persistentHeaders: Set<Header> = [],
     invoker: @escaping Invoker,
     logger: @escaping Logger = { _, _ in },
     responseMiddlewares: [ResponseMiddleware] = []
@@ -29,6 +34,7 @@ public struct API<ConstrainedType> {
     self.jsonEncoder = jsonEncoder
     self.jsonDecoder = jsonDecoder
     self.headersBuilder = headersBuilder
+    self.persistentHeaders = persistentHeaders
     self.invoker = invoker
     self.logger = logger
     self.responseMiddlewares = responseMiddlewares
diff --git a/Sources/Spyder/Builders/URLRequestBuilder.swift b/Sources/Spyder/Builders/URLRequestBuilder.swift
index 3dbf5d4..0703161 100644
--- a/Sources/Spyder/Builders/URLRequestBuilder.swift
+++ b/Sources/Spyder/Builders/URLRequestBuilder.swift
@@ -1,4 +1,7 @@
 import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
 
 public protocol URLRequestBuilder {
   static var method: HTTPMethod { get }
@@ -13,7 +16,7 @@ extension URLRequestBuilder {
   func urlRequest<ConstrainedType>(for api: API<ConstrainedType>) throws -> URLRequest {
     let mirror = Mirror(reflecting: self)
     var evaluatedPath = Self.path
-    var headers: Set<Header> = api.headersBuilder()
+    var headers: Set<Header> = api.allHeaders
     var queryItems: [URLQueryItem] = []
     var httpBody: Data?
     for child in mirror.children {
diff --git a/Tests/SpyderTests/APITests.swift b/Tests/SpyderTests/APITests.swift
index ede69f1..183a4e2 100644
--- a/Tests/SpyderTests/APITests.swift
+++ b/Tests/SpyderTests/APITests.swift
@@ -10,10 +10,10 @@ final class APITests: XCTestCase {
 
 private enum TestInvoker {
   public static let successInvoker: API.Invoker = { request in
-    .init(statusCode: 200, data: "{\"name\":\"Spyder\"}".data(using: .utf8)!)
+    .init(statusCode: 200, headers: [], data: "{\"name\":\"Spyder\"}".data(using: .utf8)!)
   }
   public static let jsonDecodingFailureInvoker: API.Invoker = { request in
-    .init(statusCode: 200, data: "{}".data(using: .utf8)!)
+    .init(statusCode: 200, headers: [], data: "{}".data(using: .utf8)!)
   }
 }
 
@@ -21,14 +21,39 @@ private enum TestInvoker {
 // MARK: Test builders
 // ========================================================================
 
-private func createSUT(invoker: @escaping API.Invoker = TestInvoker.successInvoker) -> GitHubAPI {
-  GitHubAPI.build(using: invoker)
+private func createSUT(
+  invoker: @escaping API.Invoker = TestInvoker.successInvoker,
+  headersBuilder: @escaping API.HeadersBuilder = { .init() }
+) -> GitHubAPI {
+  GitHubAPI.build(
+    using: invoker,
+    headersBuilder: headersBuilder
+  )
 }
 
 // ========================================================================
 // MARK: Tests
 // ========================================================================
 
+extension APITests {
+  func test_headers_scenarios() {
+    // Given
+    let builderHeaders: Set<Header> = .init(
+      [.init(name: "spyder-hd-builder", value: "spyder-hd-builder-value")]
+    )
+    let sut = createSUT(headersBuilder: { builderHeaders })
+    // When/Then: Before adding headers
+    XCTAssertEqual(sut.allHeaders, builderHeaders)
+    // When/Then: After adding headers
+    let additionalHeader: Header = .init(name: "spyder-additional-header", value: "spyder-additional-value")
+    sut.addHeader(additionalHeader)
+    XCTAssertEqual(sut.allHeaders, .init([
+      .init(name: "spyder-hd-builder", value: "spyder-hd-builder-value"),
+      additionalHeader
+    ]))
+  }
+}
+
 extension APITests {
   func test_invoking_happyPath() async throws {
     // Given
diff --git a/Tests/SpyderTests/GitHubAPI.swift b/Tests/SpyderTests/GitHubAPI.swift
index f29580c..aafb32c 100644
--- a/Tests/SpyderTests/GitHubAPI.swift
+++ b/Tests/SpyderTests/GitHubAPI.swift
@@ -18,12 +18,16 @@ extension GitHubAPI {
 }
 
 extension GitHubAPI {
-  static func build(using invoker: @escaping API.Invoker) -> Self {
+  static func build(
+    using invoker: @escaping API.Invoker,
+    headersBuilder: @escaping API.HeadersBuilder = { .init() }
+  ) -> GitHubAPI {
     .init(
       baseURLComponents: { components in
         components.scheme = "https"
         components.host = "api.github.com"
       },
+      headersBuilder: headersBuilder,
       invoker: invoker
     )
   }
diff --git a/Tests/SpyderTests/URLRequestBuilderTests.swift b/Tests/SpyderTests/URLRequestBuilderTests.swift
index 41a3db7..64a3061 100644
--- a/Tests/SpyderTests/URLRequestBuilderTests.swift
+++ b/Tests/SpyderTests/URLRequestBuilderTests.swift
@@ -10,6 +10,7 @@ final class URLRequestBuilderTests: XCTestCase {
 
 private func XCTAssertURLRequestEquals(
   _ request: URLRequest,
+  headers: [Header] = [],
   url: String,
   httpMethod: HTTPMethod,
   body: Data?
@@ -22,6 +23,18 @@ private func XCTAssertURLRequestEquals(
     XCTFail("Generated HTTPMethod is missing on \(request)")
     return
   }
+  if let requestHeaders = request.allHTTPHeaderFields {
+    let generatedHeaderKeys = requestHeaders.keys.sorted(by: { $0 < $1 })
+    let expectedHeaderKeys = headers.map(\.name).sorted(by: { $0 < $1 })
+    XCTAssertEqual(generatedHeaderKeys, expectedHeaderKeys)
+    expectedHeaderKeys.forEach { expectedHeaderKey in
+      let expectedHeader = headers.first(where: { $0.name == expectedHeaderKey })!
+      let generatedHeader = requestHeaders[expectedHeaderKey]!
+      XCTAssertEqual(expectedHeader.value, generatedHeader, "Header \(expectedHeader.name) is different")
+    }
+  } else if headers.isEmpty == false {
+    XCTFail("Generated headers are different expected headers \(request)")
+  }
   XCTAssertEqual(generatedURL, url)
   XCTAssertEqual(generatedHttpMethod.lowercased(), httpMethod.rawValue)
   XCTAssertEqual(request.httpBody, body)
@@ -71,6 +84,55 @@ extension URLRequestBuilderTests {
   }
 }
 
+// ========================================================================
+// MARK: URLRequestBuilderTests: Headers tests
+// ========================================================================
+
+extension URLRequestBuilderTests {
+  struct NoQueryNoPathGetWithHeadersRequestExample: URLRequestBuilder {
+    static let method: HTTPMethod = .get
+    static let path: String = "/api/v1/getRequestExample"
+    @RequestHeader(name: "spyder-auth") var auth: String
+    init(auth: String) { self.auth = auth }
+  }
+}
+
+extension URLRequestBuilderTests {
+  func test_noQueryNoPathGetRequestHeadersExample() throws {
+    // Given
+    let builder = NoQueryNoPathGetWithHeadersRequestExample(auth: "auth-value")
+    // When
+    let urlRequest = try builder.urlRequest(for: GitHubAPI.build(using: Invoker.defaultHTTPInvoker))
+    // Then
+    XCTAssertURLRequestEquals(
+      urlRequest,
+      headers: [.init(name: "spyder-auth", value: "auth-value")],
+      url: "https://api.github.com/api/v1/getRequestExample",
+      httpMethod: .get,
+      body: .none
+    )
+  }
+  func test_noQueryNoPathGetRequestHeadersAndApiHeadersExample() throws {
+    // Given
+    let builder = NoQueryNoPathGetWithHeadersRequestExample(auth: "auth-value")
+    let api = GitHubAPI.build(using: Invoker.defaultHTTPInvoker)
+    api.addHeader(.init(name: "spyder-additional-header", value: "Value!"))
+    // When
+    let urlRequest = try builder.urlRequest(for: api)
+    // Then
+    XCTAssertURLRequestEquals(
+      urlRequest,
+      headers: [
+        .init(name: "spyder-auth", value: "auth-value"),
+        .init(name: "spyder-additional-header", value: "Value!")
+      ],
+      url: "https://api.github.com/api/v1/getRequestExample",
+      httpMethod: .get,
+      body: .none
+    )
+  }
+}
+
 // ========================================================================
 // MARK: URLRequestBuilderTests: Query parameters tests
 // ========================================================================