diff --git a/modules/openapi-generator/src/main/resources/crystal/api.mustache b/modules/openapi-generator/src/main/resources/crystal/api.mustache
index 18c3d4d41e1a..0bf7d2dea886 100644
--- a/modules/openapi-generator/src/main/resources/crystal/api.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/api.mustache
@@ -23,7 +23,7 @@ module {{moduleName}}
     {{/required}}
     {{/allParams}}
     # @return [{{{returnType}}}{{^returnType}}nil{{/returnType}}]
-    def {{operationId}}({{#allParams}}{{paramName}} : {{{dataType}}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}})
+    def {{operationId}}({{#allParams}}{{paramName}} : {{{dataType}}}{{^required}}?{{/required}}{{^required}} = nil{{/required}}{{^-last}}, {{/-last}}{{/allParams}})
       {{#returnType}}data, _status_code, _headers = {{/returnType}}{{operationId}}_with_http_info({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}})
       {{#returnType}}data{{/returnType}}{{^returnType}}nil{{/returnType}}
     end
@@ -40,7 +40,7 @@ module {{moduleName}}
     {{/required}}
     {{/allParams}}
     # @return [Array<({{{returnType}}}{{^returnType}}nil{{/returnType}}, Integer, Hash)>] {{#returnType}}{{{.}}} data{{/returnType}}{{^returnType}}nil{{/returnType}}, response status code and response headers
-    def {{operationId}}_with_http_info({{#allParams}}{{paramName}} : {{{dataType}}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}})
+    def {{operationId}}_with_http_info({{#allParams}}{{paramName}} : {{{dataType}}}{{^required}}?{{/required}}{{^required}} = nil{{/required}}{{^-last}}, {{/-last}}{{/allParams}})
       if @api_client.config.debugging
         Log.debug {"Calling API: {{classname}}.{{operationId}} ..."}
       end
@@ -127,10 +127,13 @@ module {{moduleName}}
       # resource path
       local_var_path = "{{{path}}}"{{#pathParams}}.sub("{" + "{{baseName}}" + "}", URI.encode_path({{paramName}}.to_s){{^strictSpecBehavior}}.gsub("%2F", "/"){{/strictSpecBehavior}}){{/pathParams}}
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
       {{#queryParams}}
-      query_params["{{{baseName}}}"] = {{#collectionFormat}}@api_client.build_collection_param({{{paramName}}}, :{{{collectionFormat}}}){{/collectionFormat}}{{^collectionFormat}}{{{paramName}}}.to_s unless {{{paramName}}}.nil?{{/collectionFormat}}
+      query_params["{{{baseName}}}"] = {{#collectionFormat}}@api_client.build_collection_param({{{paramName}}}, :{{{collectionFormat}}}) unless {{{paramName}}}.nil?{{/collectionFormat}}{{^collectionFormat}}{{{paramName}}}.to_s unless {{{paramName}}}.nil?{{/collectionFormat}}
       {{/queryParams}}
 
       # header parameters
@@ -170,6 +173,7 @@ module {{moduleName}}
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: {{classname}}#{{operationId}}\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
diff --git a/modules/openapi-generator/src/main/resources/crystal/api_client.mustache b/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
index 6092a89911c6..b74d38f191b3 100644
--- a/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/api_client.mustache
@@ -50,14 +50,15 @@ module {{moduleName}}
     # @param [Hash] header_params Header parameters
     # @param [Hash] query_params Query parameters
     # @param [String] auth_names Authentication scheme name
-    def update_params_for_auth!(header_params, query_params, auth_names)
+    def update_params_for_auth!(header_params, query_params, cookie_params, auth_names)
       auth_names.each do |auth_name|
         auth_setting = @config.auth_settings[auth_name]
         next unless auth_setting
         case auth_setting[:in]
         when "header" then header_params[auth_setting[:key]] = auth_setting[:value]
         when "query"  then query_params[auth_setting[:key]] = auth_setting[:value]
-        else raise ArgumentError.new("Authentication token must be in `query` of `header`")
+        when "cookie" then cookie_params[auth_setting[:key]] = auth_setting[:value]
+        else raise ArgumentError.new("Authentication token must be in `cookie`, `query` or `header`")
         end
       end
     end
@@ -119,7 +120,7 @@ module {{moduleName}}
     #
     # @return [Array<(Object, Integer, Hash)>] an array of 3 elements:
     #   the data deserialized from response body (could be nil), response status code and response headers.
-    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String?, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, form_params = {} of Symbol => (String | ::File))
+    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String?, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, cookie_params = {} of String => String, form_params = {} of Symbol => (String | ::File))
       #ssl_options = {
       #  :ca_file => @config.ssl_ca_file,
       #  :verify => @config.ssl_verify,
@@ -128,7 +129,7 @@ module {{moduleName}}
       #  :client_key => @config.ssl_client_key
       #}
 
-      update_params_for_auth! header_params, query_params, auth_names
+      update_params_for_auth! header_params, query_params, cookie_params, auth_names
 
       if !post_body.nil? && !post_body.empty?
         # use JSON string in the payload
@@ -143,7 +144,7 @@ module {{moduleName}}
         build_request_url(path, operation),
         params: query_params,
         headers: header_params,
-        #cookies: cookie_params, # TODO add cookies support
+        cookies: cookie_params,
         form: form_or_body,
         logging: @config.debugging,
         handle_errors: false
diff --git a/modules/openapi-generator/src/main/resources/crystal/model.mustache b/modules/openapi-generator/src/main/resources/crystal/model.mustache
index 3330b7ad234f..8b06bff97597 100644
--- a/modules/openapi-generator/src/main/resources/crystal/model.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/model.mustache
@@ -2,6 +2,7 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module {{moduleName}}
diff --git a/modules/openapi-generator/src/main/resources/crystal/partial_model_generic.mustache b/modules/openapi-generator/src/main/resources/crystal/partial_model_generic.mustache
index ba58fb06828e..3daff8530465 100644
--- a/modules/openapi-generator/src/main/resources/crystal/partial_model_generic.mustache
+++ b/modules/openapi-generator/src/main/resources/crystal/partial_model_generic.mustache
@@ -3,6 +3,7 @@
   {{/description}}
   class {{classname}}{{#parent}} < {{{.}}}{{/parent}}
     include JSON::Serializable
+    include YAML::Serializable
 
     {{#hasRequired}}
     # Required properties
@@ -269,16 +270,16 @@
     {{/vars}}
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class{{#vars}} &&
-          {{name}} == o.{{name}}{{/vars}}{{#parent}} && super(o){{/parent}}
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class{{#vars}} &&
+          {{name}} == other.{{name}}{{/vars}}{{#parent}} && super(other){{/parent}}
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/bin/ameba b/samples/client/petstore/crystal/bin/ameba
index c88ac4a8d026..e708bbed7199 100755
Binary files a/samples/client/petstore/crystal/bin/ameba and b/samples/client/petstore/crystal/bin/ameba differ
diff --git a/samples/client/petstore/crystal/spec/api_client_spec.cr b/samples/client/petstore/crystal/spec/api_client_spec.cr
index eb6ee5723678..767764436a92 100644
--- a/samples/client/petstore/crystal/spec/api_client_spec.cr
+++ b/samples/client/petstore/crystal/spec/api_client_spec.cr
@@ -9,9 +9,10 @@ Spectator.describe Petstore::ApiClient do
 
         header_params = {} of String => String
         query_params = {} of String => String
+        cookie_params = {} of String => String
 
         api_client = Petstore::ApiClient.new(config)
-        api_client.update_params_for_auth!(header_params, query_params, ["petstore_auth"])
+        api_client.update_params_for_auth!(header_params, query_params, cookie_params, ["petstore_auth"])
 
         expect(header_params["Authorization"]).to eq "Bearer xxx"
         expect(query_params.size).to eq 0
@@ -26,9 +27,10 @@ Spectator.describe Petstore::ApiClient do
 
           header_params = {} of String => String
           query_params = {} of String => String
+          cookie_params = {} of String => String
 
           api_client = Petstore::ApiClient.new(config)
-          api_client.update_params_for_auth!(header_params, query_params, ["api_key"])
+          api_client.update_params_for_auth!(header_params, query_params, cookie_params, ["api_key"])
 
           expect(header_params["api_key"]).to eq "xxx"
           expect(query_params.empty?).to be_true
@@ -43,9 +45,10 @@ Spectator.describe Petstore::ApiClient do
 
           header_params = {} of String => String
           query_params = {} of String => String
+          cookie_params = {} of String => String
 
           api_client = Petstore::ApiClient.new(config)
-          api_client.update_params_for_auth!(header_params, query_params, ["api_key"])
+          api_client.update_params_for_auth!(header_params, query_params, cookie_params, ["api_key"])
 
           expect(header_params["api_key"]).to eq "Token xxx"
           expect(query_params.empty?).to be_true
diff --git a/samples/client/petstore/crystal/src/petstore/api/fake_api.cr b/samples/client/petstore/crystal/src/petstore/api/fake_api.cr
index de491cde9194..63b653670e51 100644
--- a/samples/client/petstore/crystal/src/petstore/api/fake_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/fake_api.cr
@@ -63,6 +63,9 @@ module Petstore
       # resource path
       local_var_path = "/fake/parameter-name-mapping"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
       query_params["type"] = _type.to_s unless _type.nil?
@@ -94,6 +97,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: FakeApi#get_parameter_name_mapping\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
diff --git a/samples/client/petstore/crystal/src/petstore/api/pet_api.cr b/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
index 613d925af861..3d53e092bcd6 100644
--- a/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/pet_api.cr
@@ -41,6 +41,9 @@ module Petstore
       # resource path
       local_var_path = "/pet"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -71,6 +74,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#add_pet\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -82,7 +86,7 @@ module Petstore
     # 
     # @param pet_id [Int64] Pet id to delete
     # @return [nil]
-    def delete_pet(pet_id : Int64, api_key : String?)
+    def delete_pet(pet_id : Int64, api_key : String? = nil)
       delete_pet_with_http_info(pet_id, api_key)
       nil
     end
@@ -91,7 +95,7 @@ module Petstore
     # 
     # @param pet_id [Int64] Pet id to delete
     # @return [Array<(nil, Integer, Hash)>] nil, response status code and response headers
-    def delete_pet_with_http_info(pet_id : Int64, api_key : String?)
+    def delete_pet_with_http_info(pet_id : Int64, api_key : String? = nil)
       if @api_client.config.debugging
         Log.debug {"Calling API: PetApi.delete_pet ..."}
       end
@@ -102,6 +106,9 @@ module Petstore
       # resource path
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode_path(pet_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -129,6 +136,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#delete_pet\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -160,9 +168,12 @@ module Petstore
       # resource path
       local_var_path = "/pet/findByStatus"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
-      query_params["status"] = @api_client.build_collection_param(status, :csv)
+      query_params["status"] = @api_client.build_collection_param(status, :csv) unless status.nil?
 
       # header parameters
       header_params = Hash(String, String).new
@@ -189,6 +200,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#find_pets_by_status\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -220,9 +232,12 @@ module Petstore
       # resource path
       local_var_path = "/pet/findByTags"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
-      query_params["tags"] = @api_client.build_collection_param(tags, :csv)
+      query_params["tags"] = @api_client.build_collection_param(tags, :csv) unless tags.nil?
 
       # header parameters
       header_params = Hash(String, String).new
@@ -249,6 +264,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#find_pets_by_tags\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -280,6 +296,9 @@ module Petstore
       # resource path
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode_path(pet_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -308,6 +327,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#get_pet_by_id\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -339,6 +359,9 @@ module Petstore
       # resource path
       local_var_path = "/pet"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -369,6 +392,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#update_pet\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -380,7 +404,7 @@ module Petstore
     # 
     # @param pet_id [Int64] ID of pet that needs to be updated
     # @return [nil]
-    def update_pet_with_form(pet_id : Int64, name : String?, status : String?)
+    def update_pet_with_form(pet_id : Int64, name : String? = nil, status : String? = nil)
       update_pet_with_form_with_http_info(pet_id, name, status)
       nil
     end
@@ -389,7 +413,7 @@ module Petstore
     # 
     # @param pet_id [Int64] ID of pet that needs to be updated
     # @return [Array<(nil, Integer, Hash)>] nil, response status code and response headers
-    def update_pet_with_form_with_http_info(pet_id : Int64, name : String?, status : String?)
+    def update_pet_with_form_with_http_info(pet_id : Int64, name : String? = nil, status : String? = nil)
       if @api_client.config.debugging
         Log.debug {"Calling API: PetApi.update_pet_with_form ..."}
       end
@@ -400,6 +424,9 @@ module Petstore
       # resource path
       local_var_path = "/pet/{petId}".sub("{" + "petId" + "}", URI.encode_path(pet_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -430,6 +457,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#update_pet_with_form\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -441,7 +469,7 @@ module Petstore
     # 
     # @param pet_id [Int64] ID of pet to update
     # @return [ApiResponse]
-    def upload_file(pet_id : Int64, additional_metadata : String?, file : ::File?)
+    def upload_file(pet_id : Int64, additional_metadata : String? = nil, file : ::File? = nil)
       data, _status_code, _headers = upload_file_with_http_info(pet_id, additional_metadata, file)
       data
     end
@@ -450,7 +478,7 @@ module Petstore
     # 
     # @param pet_id [Int64] ID of pet to update
     # @return [Array<(ApiResponse, Integer, Hash)>] ApiResponse data, response status code and response headers
-    def upload_file_with_http_info(pet_id : Int64, additional_metadata : String?, file : ::File?)
+    def upload_file_with_http_info(pet_id : Int64, additional_metadata : String? = nil, file : ::File? = nil)
       if @api_client.config.debugging
         Log.debug {"Calling API: PetApi.upload_file ..."}
       end
@@ -461,6 +489,9 @@ module Petstore
       # resource path
       local_var_path = "/pet/{petId}/uploadImage".sub("{" + "petId" + "}", URI.encode_path(pet_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -493,6 +524,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: PetApi#upload_file\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
diff --git a/samples/client/petstore/crystal/src/petstore/api/store_api.cr b/samples/client/petstore/crystal/src/petstore/api/store_api.cr
index 87ed25f1ff4d..ae2479ca06b3 100644
--- a/samples/client/petstore/crystal/src/petstore/api/store_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/store_api.cr
@@ -41,6 +41,9 @@ module Petstore
       # resource path
       local_var_path = "/store/order/{orderId}".sub("{" + "orderId" + "}", URI.encode_path(order_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -67,6 +70,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: StoreApi#delete_order\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -92,6 +96,9 @@ module Petstore
       # resource path
       local_var_path = "/store/inventory"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -120,6 +127,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: StoreApi#get_inventory\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -159,6 +167,9 @@ module Petstore
       # resource path
       local_var_path = "/store/order/{orderId}".sub("{" + "orderId" + "}", URI.encode_path(order_id.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -187,6 +198,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: StoreApi#get_order_by_id\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -218,6 +230,9 @@ module Petstore
       # resource path
       local_var_path = "/store/order"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -248,6 +263,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: StoreApi#place_order\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
diff --git a/samples/client/petstore/crystal/src/petstore/api/user_api.cr b/samples/client/petstore/crystal/src/petstore/api/user_api.cr
index c94493b05005..74b9d43e3725 100644
--- a/samples/client/petstore/crystal/src/petstore/api/user_api.cr
+++ b/samples/client/petstore/crystal/src/petstore/api/user_api.cr
@@ -41,6 +41,9 @@ module Petstore
       # resource path
       local_var_path = "/user"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -69,6 +72,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#create_user\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -100,6 +104,9 @@ module Petstore
       # resource path
       local_var_path = "/user/createWithArray"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -128,6 +135,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#create_users_with_array_input\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -159,6 +167,9 @@ module Petstore
       # resource path
       local_var_path = "/user/createWithList"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -187,6 +198,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#create_users_with_list_input\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -218,6 +230,9 @@ module Petstore
       # resource path
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode_path(username.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -244,6 +259,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#delete_user\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -275,6 +291,9 @@ module Petstore
       # resource path
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode_path(username.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -303,6 +322,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#get_user_by_name\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -345,6 +365,9 @@ module Petstore
       # resource path
       local_var_path = "/user/login"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
       query_params["username"] = username.to_s unless username.nil?
@@ -375,6 +398,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#login_user\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -400,6 +424,9 @@ module Petstore
       # resource path
       local_var_path = "/user/logout"
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -426,6 +453,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#logout_user\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
@@ -463,6 +491,9 @@ module Petstore
       # resource path
       local_var_path = "/user/{username}".sub("{" + "username" + "}", URI.encode_path(username.to_s).gsub("%2F", "/"))
 
+      # cookie parameters
+      cookie_params = Hash(String, String).new
+
       # query parameters
       query_params = Hash(String, String).new
 
@@ -491,6 +522,7 @@ module Petstore
                                                         auth_names,
                                                         header_params,
                                                         query_params,
+                                                        cookie_params,
                                                         form_params)
       if @api_client.config.debugging
         Log.debug {"API called: UserApi#update_user\nData: #{data.inspect}\nStatus code: #{status_code}\nHeaders: #{headers}"}
diff --git a/samples/client/petstore/crystal/src/petstore/api_client.cr b/samples/client/petstore/crystal/src/petstore/api_client.cr
index 256c623056d9..b2479e7aae43 100644
--- a/samples/client/petstore/crystal/src/petstore/api_client.cr
+++ b/samples/client/petstore/crystal/src/petstore/api_client.cr
@@ -58,14 +58,15 @@ module Petstore
     # @param [Hash] header_params Header parameters
     # @param [Hash] query_params Query parameters
     # @param [String] auth_names Authentication scheme name
-    def update_params_for_auth!(header_params, query_params, auth_names)
+    def update_params_for_auth!(header_params, query_params, cookie_params, auth_names)
       auth_names.each do |auth_name|
         auth_setting = @config.auth_settings[auth_name]
         next unless auth_setting
         case auth_setting[:in]
         when "header" then header_params[auth_setting[:key]] = auth_setting[:value]
         when "query"  then query_params[auth_setting[:key]] = auth_setting[:value]
-        else raise ArgumentError.new("Authentication token must be in `query` of `header`")
+        when "cookie" then cookie_params[auth_setting[:key]] = auth_setting[:value]
+        else raise ArgumentError.new("Authentication token must be in `cookie`, `query` or `header`")
         end
       end
     end
@@ -127,7 +128,7 @@ module Petstore
     #
     # @return [Array<(Object, Integer, Hash)>] an array of 3 elements:
     #   the data deserialized from response body (could be nil), response status code and response headers.
-    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String?, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, form_params = {} of Symbol => (String | ::File))
+    def call_api(http_method : Symbol, path : String, operation : Symbol, return_type : String?, post_body : String?, auth_names = [] of String, header_params = {} of String => String, query_params = {} of String => String, cookie_params = {} of String => String, form_params = {} of Symbol => (String | ::File))
       #ssl_options = {
       #  :ca_file => @config.ssl_ca_file,
       #  :verify => @config.ssl_verify,
@@ -136,7 +137,7 @@ module Petstore
       #  :client_key => @config.ssl_client_key
       #}
 
-      update_params_for_auth! header_params, query_params, auth_names
+      update_params_for_auth! header_params, query_params, cookie_params, auth_names
 
       if !post_body.nil? && !post_body.empty?
         # use JSON string in the payload
@@ -151,7 +152,7 @@ module Petstore
         build_request_url(path, operation),
         params: query_params,
         headers: header_params,
-        #cookies: cookie_params, # TODO add cookies support
+        cookies: cookie_params,
         form: form_or_body,
         logging: @config.debugging,
         handle_errors: false
diff --git a/samples/client/petstore/crystal/src/petstore/models/another_property_name_mapping.cr b/samples/client/petstore/crystal/src/petstore/models/another_property_name_mapping.cr
index 3d4789fa45a6..905e388481ad 100644
--- a/samples/client/petstore/crystal/src/petstore/models/another_property_name_mapping.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/another_property_name_mapping.cr
@@ -10,11 +10,13 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   class AnotherPropertyNameMapping
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "http_debug_operation", type: String?, nillable: true, emit_null: false)]
@@ -49,19 +51,19 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          http_debug_operation == o.http_debug_operation &&
-          underscore_type == o.underscore_type &&
-          _type == o._type &&
-          type_with_underscore == o.type_with_underscore
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          http_debug_operation == other.http_debug_operation &&
+          underscore_type == other.underscore_type &&
+          _type == other._type &&
+          type_with_underscore == other.type_with_underscore
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/api_response.cr b/samples/client/petstore/crystal/src/petstore/models/api_response.cr
index a77a0e108b8d..985f79f46243 100644
--- a/samples/client/petstore/crystal/src/petstore/models/api_response.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/api_response.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # Describes the result of uploading an image resource
   class ApiResponse
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "code", type: Int32?, nillable: true, emit_null: false)]
@@ -47,18 +49,18 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          code == o.code &&
-          _type == o._type &&
-          message == o.message
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          code == other.code &&
+          _type == other._type &&
+          message == other.message
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/category.cr b/samples/client/petstore/crystal/src/petstore/models/category.cr
index 622e67e40873..f690db207604 100644
--- a/samples/client/petstore/crystal/src/petstore/models/category.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/category.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # A category for a pet
   class Category
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "id", type: Int64?, nillable: true, emit_null: false)]
@@ -61,17 +63,17 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          id == o.id &&
-          name == o.name
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          id == other.id &&
+          name == other.name
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/format_test.cr b/samples/client/petstore/crystal/src/petstore/models/format_test.cr
index 570a1b6df517..4a19a070db86 100644
--- a/samples/client/petstore/crystal/src/petstore/models/format_test.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/format_test.cr
@@ -10,11 +10,13 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   class FormatTest
     include JSON::Serializable
+    include YAML::Serializable
 
     # Required properties
     @[JSON::Field(key: "number", type: Float64, nillable: false, emit_null: false)]
@@ -283,31 +285,31 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          integer == o.integer &&
-          int32 == o.int32 &&
-          int64 == o.int64 &&
-          number == o.number &&
-          float == o.float &&
-          double == o.double &&
-          decimal == o.decimal &&
-          string == o.string &&
-          byte == o.byte &&
-          binary == o.binary &&
-          date == o.date &&
-          date_time == o.date_time &&
-          uuid == o.uuid &&
-          password == o.password &&
-          pattern_with_digits == o.pattern_with_digits &&
-          pattern_with_digits_and_delimiter == o.pattern_with_digits_and_delimiter
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          integer == other.integer &&
+          int32 == other.int32 &&
+          int64 == other.int64 &&
+          number == other.number &&
+          float == other.float &&
+          double == other.double &&
+          decimal == other.decimal &&
+          string == other.string &&
+          byte == other.byte &&
+          binary == other.binary &&
+          date == other.date &&
+          date_time == other.date_time &&
+          uuid == other.uuid &&
+          password == other.password &&
+          pattern_with_digits == other.pattern_with_digits &&
+          pattern_with_digits_and_delimiter == other.pattern_with_digits_and_delimiter
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/order.cr b/samples/client/petstore/crystal/src/petstore/models/order.cr
index 056d81b0378f..3a63d89d68be 100644
--- a/samples/client/petstore/crystal/src/petstore/models/order.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/order.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # An order for a pets from the pet store
   class Order
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "id", type: Int64?, nillable: true, emit_null: false)]
@@ -92,21 +94,21 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          id == o.id &&
-          pet_id == o.pet_id &&
-          quantity == o.quantity &&
-          ship_date == o.ship_date &&
-          status == o.status &&
-          complete == o.complete
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          id == other.id &&
+          pet_id == other.pet_id &&
+          quantity == other.quantity &&
+          ship_date == other.ship_date &&
+          status == other.status &&
+          complete == other.complete
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/pet.cr b/samples/client/petstore/crystal/src/petstore/models/pet.cr
index 50b13cc251ba..d0ff4c3ecc04 100644
--- a/samples/client/petstore/crystal/src/petstore/models/pet.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/pet.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # A pet for sale in the pet store
   class Pet
     include JSON::Serializable
+    include YAML::Serializable
 
     # Required properties
     @[JSON::Field(key: "name", type: String, nillable: false, emit_null: false)]
@@ -93,21 +95,21 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          id == o.id &&
-          category == o.category &&
-          name == o.name &&
-          photo_urls == o.photo_urls &&
-          tags == o.tags &&
-          status == o.status
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          id == other.id &&
+          category == other.category &&
+          name == other.name &&
+          photo_urls == other.photo_urls &&
+          tags == other.tags &&
+          status == other.status
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/tag.cr b/samples/client/petstore/crystal/src/petstore/models/tag.cr
index 6514d7cf962a..0917d787612b 100644
--- a/samples/client/petstore/crystal/src/petstore/models/tag.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/tag.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # A tag for a pet
   class Tag
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "id", type: Int64?, nillable: true, emit_null: false)]
@@ -44,17 +46,17 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          id == o.id &&
-          name == o.name
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          id == other.id &&
+          name == other.name
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.
diff --git a/samples/client/petstore/crystal/src/petstore/models/user.cr b/samples/client/petstore/crystal/src/petstore/models/user.cr
index a70147b19b3b..fb68d42f8649 100644
--- a/samples/client/petstore/crystal/src/petstore/models/user.cr
+++ b/samples/client/petstore/crystal/src/petstore/models/user.cr
@@ -10,12 +10,14 @@
 
 require "big"
 require "json"
+require "yaml"
 require "time"
 
 module Petstore
   # A User who is purchasing from the pet store
   class User
     include JSON::Serializable
+    include YAML::Serializable
 
     # Optional properties
     @[JSON::Field(key: "id", type: Int64?, nillable: true, emit_null: false)]
@@ -63,23 +65,23 @@ module Petstore
 
     # Checks equality by comparing each attribute.
     # @param [Object] Object to be compared
-    def ==(o)
-      return true if self.same?(o)
-      self.class == o.class &&
-          id == o.id &&
-          username == o.username &&
-          first_name == o.first_name &&
-          last_name == o.last_name &&
-          email == o.email &&
-          password == o.password &&
-          phone == o.phone &&
-          user_status == o.user_status
+    def ==(other)
+      return true if self.same?(other)
+      self.class == other.class &&
+          id == other.id &&
+          username == other.username &&
+          first_name == other.first_name &&
+          last_name == other.last_name &&
+          email == other.email &&
+          password == other.password &&
+          phone == other.phone &&
+          user_status == other.user_status
     end
 
     # @see the `==` method
     # @param [Object] Object to be compared
-    def eql?(o)
-      self == o
+    def eql?(other)
+      self == other
     end
 
     # Calculates hash code according to all attributes.