diff --git a/.credo.exs b/.credo.exs
new file mode 100644
index 0000000..9304539
--- /dev/null
+++ b/.credo.exs
@@ -0,0 +1,159 @@
+# This file contains the configuration for Credo and you are probably reading
+# this after creating it with `mix credo.gen.config`.
+#
+# If you find anything wrong or unclear in this file, please report an
+# issue on GitHub: https://github.com/rrrene/credo/issues
+#
+%{
+  #
+  # You can have as many configs as you like in the `configs:` field.
+  configs: [
+    %{
+      #
+      # Run any exec using `mix credo -C <name>`. If no exec name is given
+      # "default" is used.
+      #
+      name: "default",
+      #
+      # These are the files included in the analysis:
+      files: %{
+        #
+        # You can give explicit globs or simply directories.
+        # In the latter case `**/*.{ex,exs}` will be used.
+        #
+        included: ["lib/", "src/", "test/", "web/", "apps/"],
+        excluded: [~r"/_build/", ~r"/deps/"]
+      },
+      #
+      # If you create your own checks, you must specify the source files for
+      # them here, so they can be loaded by Credo before running the analysis.
+      #
+      requires: [],
+      #
+      # If you want to enforce a style guide and need a more traditional linting
+      # experience, you can change `strict` to `true` below:
+      #
+      strict: false,
+      #
+      # If you want to use uncolored output by default, you can change `color`
+      # to `false` below:
+      #
+      color: true,
+      #
+      # You can customize the parameters of any check by adding a second element
+      # to the tuple.
+      #
+      # To disable a check put `false` as second element:
+      #
+      #     {Credo.Check.Design.DuplicatedCode, false}
+      #
+      checks: [
+        #
+        ## Consistency Checks
+        #
+        {Credo.Check.Consistency.ExceptionNames},
+        {Credo.Check.Consistency.LineEndings},
+        {Credo.Check.Consistency.ParameterPatternMatching},
+        {Credo.Check.Consistency.SpaceAroundOperators},
+        {Credo.Check.Consistency.SpaceInParentheses},
+        {Credo.Check.Consistency.TabsOrSpaces},
+
+        #
+        ## Design Checks
+        #
+        # You can customize the priority of any check
+        # Priority values are: `low, normal, high, higher`
+        #
+        {Credo.Check.Design.AliasUsage, priority: :low},
+        # For some checks, you can also set other parameters
+        #
+        # If you don't want the `setup` and `test` macro calls in ExUnit tests
+        # or the `schema` macro in Ecto schemas to trigger DuplicatedCode, just
+        # set the `excluded_macros` parameter to `[:schema, :setup, :test]`.
+        #
+        {Credo.Check.Design.DuplicatedCode, excluded_macros: []},
+        # You can also customize the exit_status of each check.
+        # If you don't want TODO comments to cause `mix credo` to fail, just
+        # set this value to 0 (zero).
+        #
+        {Credo.Check.Design.TagTODO, exit_status: 0},
+        {Credo.Check.Design.TagFIXME},
+
+        #
+        ## Readability Checks
+        #
+        {Credo.Check.Readability.FunctionNames},
+        {Credo.Check.Readability.LargeNumbers},
+        {Credo.Check.Readability.MaxLineLength, priority: :low, max_length: 80},
+        {Credo.Check.Readability.ModuleAttributeNames},
+        {Credo.Check.Readability.ModuleDoc},
+        {Credo.Check.Readability.ModuleNames},
+        {Credo.Check.Readability.ParenthesesOnZeroArityDefs},
+        {Credo.Check.Readability.ParenthesesInCondition},
+        {Credo.Check.Readability.PredicateFunctionNames},
+        {Credo.Check.Readability.PreferImplicitTry},
+        {Credo.Check.Readability.RedundantBlankLines},
+        {Credo.Check.Readability.StringSigils},
+        {Credo.Check.Readability.TrailingBlankLine},
+        {Credo.Check.Readability.TrailingWhiteSpace},
+        {Credo.Check.Readability.VariableNames},
+        {Credo.Check.Readability.Semicolons},
+        {Credo.Check.Readability.SpaceAfterCommas},
+
+        #
+        ## Refactoring Opportunities
+        #
+        {Credo.Check.Refactor.DoubleBooleanNegation},
+        {Credo.Check.Refactor.CondStatements},
+        {Credo.Check.Refactor.CyclomaticComplexity},
+        {Credo.Check.Refactor.FunctionArity},
+        {Credo.Check.Refactor.LongQuoteBlocks},
+        {Credo.Check.Refactor.MatchInCondition},
+        {Credo.Check.Refactor.NegatedConditionsInUnless},
+        {Credo.Check.Refactor.NegatedConditionsWithElse},
+        {Credo.Check.Refactor.Nesting},
+        {Credo.Check.Refactor.PipeChainStart,
+         excluded_argument_types: [:atom, :binary, :fn, :keyword], excluded_functions: []},
+        {Credo.Check.Refactor.UnlessWithElse},
+
+        #
+        ## Warnings
+        #
+        {Credo.Check.Warning.BoolOperationOnSameValues},
+        {Credo.Check.Warning.ExpensiveEmptyEnumCheck},
+        {Credo.Check.Warning.IExPry},
+        {Credo.Check.Warning.IoInspect},
+        {Credo.Check.Warning.LazyLogging},
+        {Credo.Check.Warning.OperationOnSameValues},
+        {Credo.Check.Warning.OperationWithConstantResult},
+        {Credo.Check.Warning.UnusedEnumOperation},
+        {Credo.Check.Warning.UnusedFileOperation},
+        {Credo.Check.Warning.UnusedKeywordOperation},
+        {Credo.Check.Warning.UnusedListOperation},
+        {Credo.Check.Warning.UnusedPathOperation},
+        {Credo.Check.Warning.UnusedRegexOperation},
+        {Credo.Check.Warning.UnusedStringOperation},
+        {Credo.Check.Warning.UnusedTupleOperation},
+        {Credo.Check.Warning.RaiseInsideRescue},
+
+        #
+        # Controversial and experimental checks (opt-in, just remove `, false`)
+        #
+        {Credo.Check.Refactor.ABCSize, false},
+        {Credo.Check.Refactor.AppendSingleItem, false},
+        {Credo.Check.Refactor.VariableRebinding, false},
+        {Credo.Check.Warning.MapGetUnsafePass, false},
+        {Credo.Check.Consistency.MultiAliasImportRequireUse, false},
+
+        #
+        # Deprecated checks (these will be deleted after a grace period)
+        #
+        {Credo.Check.Readability.Specs, false}
+
+        #
+        # Custom checks can be created using `mix credo.gen.check`.
+        #
+      ]
+    }
+  ]
+}
diff --git a/.travis.yml b/.travis.yml
index fe06704..d4c6560 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,6 +16,7 @@ install:
   - mix deps.get
 script:
   - mix test
+  - mix credo
 matrix:
   exclude:
     - elixir: 1.3.4
diff --git a/lib/catalog_api.ex b/lib/catalog_api.ex
index d86f5fb..7db6c49 100644
--- a/lib/catalog_api.ex
+++ b/lib/catalog_api.ex
@@ -196,7 +196,7 @@ defmodule CatalogApi do
           | {:error, {:catalog_api_fault, Error.extracted_fault()}}
           | {:error, Poison.ParseError.t()}
           | {:error, :unparseable_response_description}
-  def cart_set_address(socket_id, external_user_id, address = %Address{}) do
+  def cart_set_address(socket_id, external_user_id, %Address{} = address) do
     address_params = Map.from_struct(address)
     cart_set_address(socket_id, external_user_id, address_params)
   end
@@ -613,7 +613,9 @@ defmodule CatalogApi do
   """
   def order_list(external_user_id, opts \\ []) do
     defaults = [per_page: 10, page: 1]
-    %{per_page: per_page, page: page} = Keyword.merge(defaults, opts) |> Enum.into(%{})
+    %{per_page: per_page, page: page} = defaults 
+                                        |> Keyword.merge(opts) 
+                                        |> Enum.into(%{})
 
     # TODO: validate that per_page is at most 50.
 
diff --git a/lib/catalog_api/address.ex b/lib/catalog_api/address.ex
index 87eb0d3..cdf13a5 100644
--- a/lib/catalog_api/address.ex
+++ b/lib/catalog_api/address.ex
@@ -313,12 +313,10 @@ defmodule CatalogApi.Address do
   def validate_field(_field, _value), do: %{}
 
   defp validate_field_length(field, value, max_length) when is_binary(value) do
-    cond do
-      String.length(value) > max_length ->
-        %{field => ["cannot be longer than #{max_length} characters"]}
-
-      true ->
-        %{}
+    if String.length(value) > max_length do
+      %{field => ["cannot be longer than #{max_length} characters"]}
+    else
+      %{}
     end
   end
 end
diff --git a/lib/catalog_api/coercion.ex b/lib/catalog_api/coercion.ex
index 37f05b9..cc7e400 100644
--- a/lib/catalog_api/coercion.ex
+++ b/lib/catalog_api/coercion.ex
@@ -15,9 +15,10 @@ defmodule CatalogApi.Coercion do
   @spec coerce_to_boolean_if_needed(String.t() | atom(), any(), list(String.t() | atom())) ::
           {String.t(), any()}
   defp coerce_to_boolean_if_needed(key, value, boolean_fields) do
-    cond do
-      key in boolean_fields -> {key, coerce_integer_to_boolean(value)}
-      true -> {key, value}
+    if key in boolean_fields do
+      {key, coerce_integer_to_boolean(value)}
+    else
+      {key, value}
     end
   end
 
@@ -42,9 +43,10 @@ defmodule CatalogApi.Coercion do
   @spec coerce_to_integer_if_needed(String.t() | atom(), any(), list(Strin.t() | atom())) ::
           {String.t(), any()}
   defp coerce_to_integer_if_needed(key, value, boolean_fields) do
-    cond do
-      key in boolean_fields -> {key, coerce_boolean_to_integer(value)}
-      true -> {key, value}
+    if key in boolean_fields do
+      {key, coerce_boolean_to_integer(value)}
+    else
+      {key, value}
     end
   end
 
diff --git a/mix.exs b/mix.exs
index 496d6ec..400d2f2 100644
--- a/mix.exs
+++ b/mix.exs
@@ -27,6 +27,7 @@ defmodule CatalogApi.Mixfile do
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     [
+      {:credo, "~> 0.9.1", only: [:dev, :test], runtime: false},
       {:ex_doc, "~> 0.16", only: :dev, runtime: false},
       {:httpoison, "~> 1.0"},
       {:mock, "~> 0.3.0", only: :test},
diff --git a/mix.lock b/mix.lock
index af5b0b6..106d8d5 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,5 +1,7 @@
 %{
+  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm"},
   "certifi": {:hex, :certifi, "2.0.0", "a0c0e475107135f76b8c1d5bc7efb33cd3815cb3cf3dea7aefdd174dabead064", [:rebar3], [], "hexpm"},
+  "credo": {:hex, :credo, "0.9.2", "841d316612f568beb22ba310d816353dddf31c2d94aa488ae5a27bb53760d0bf", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:poison, ">= 0.0.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.4", "99b637c62a4d65a20a9fb674b8cffb8baa771c04605a80c911c4418c69b75439", [:mix], [], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.18.2", "993e0a95e9fbb790ac54ea58e700b45b299bd48bc44b4ae0404f28161f37a83e", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"},
   "hackney": {:hex, :hackney, "1.11.0", "4951ee019df102492dabba66a09e305f61919a8a183a7860236c0fde586134b6", [:rebar3], [{:certifi, "2.0.0", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "5.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
diff --git a/test/catalog_api/address_test.exs b/test/catalog_api/address_test.exs
index 04b998a..00acd34 100644
--- a/test/catalog_api/address_test.exs
+++ b/test/catalog_api/address_test.exs
@@ -57,7 +57,8 @@ defmodule CatalogApi.AddressTest do
 
     test "returns :ok for valid address params when params have mixed keys" do
       params =
-        Map.put(@valid_address_params, :city, "Cleveland")
+        @valid_address_params
+        |> Map.put(:city, "Cleveland")
         |> Map.delete("city")
 
       assert :ok = Address.validate_params(params)
diff --git a/test/support/fixture_helper.ex b/test/support/fixture_helper.ex
index 7d98203..8db1093 100644
--- a/test/support/fixture_helper.ex
+++ b/test/support/fixture_helper.ex
@@ -1,4 +1,6 @@
 defmodule CatalogApi.FixtureHelper do
+  @moduledoc false
+
   @response_headers [
     {"Access-Control-Allow-Methods", "GET"},
     {"Access-Control-Allow-Origin", "*"},
@@ -19,7 +21,7 @@ defmodule CatalogApi.FixtureHelper do
   end
 
   def retrieve_json_fixture(fixture_name) do
-    retrieve_fixture("#{fixture_name}.json") |> Poison.decode!()
+    "#{fixture_name}.json" |> retrieve_fixture |> Poison.decode!()
   end
 
   def retrieve_json_response(fixture_name, status_code \\ 200) do
diff --git a/test/support/format_helper.ex b/test/support/format_helper.ex
index d15dde1..edbde97 100644
--- a/test/support/format_helper.ex
+++ b/test/support/format_helper.ex
@@ -1,4 +1,6 @@
 defmodule CatalogApi.FormatHelper do
+  @moduledoc false
+
   def is_iso8601_datetime_string(datetime) when is_binary(datetime) do
     case datetime do
       <<_year::bytes-size(4)>> <>