diff --git a/.gitignore b/.gitignore
index d7a22a8..0c1b96a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 **/*/node_modules
 *.swp
 Gemfile.lock
+/.idea/
diff --git a/.ruby-version b/.ruby-version
index 2bf1c1c..73462a5 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.3.1
+2.5.1
diff --git a/Gemfile b/Gemfile
index bbd3d73..1abf797 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ when '4', '5'
   gem 'responders'
 end
 
-gem 'sqlite3'
+gem 'sqlite3', '~> 1.3.6'
 
 gem 'rswag-api', path: './rswag-api'
 gem 'rswag-ui', path: './rswag-ui'
diff --git a/rswag-specs/lib/rswag/specs/example_group_helpers.rb b/rswag-specs/lib/rswag/specs/example_group_helpers.rb
index c293c63..2e2fd7d 100644
--- a/rswag-specs/lib/rswag/specs/example_group_helpers.rb
+++ b/rswag-specs/lib/rswag/specs/example_group_helpers.rb
@@ -35,6 +35,14 @@ module Rswag
         end
       end
 
+      #TODO: look at adding request_body method to handle diffs in Open API 2.0 to 3.0
+      # https://swagger.io/docs/specification/describing-request-body/
+      # need to make sure we output requestBody in the swagger generator .json
+      # also need to make sure that it can handle content: , required: true/false, schema: ref
+
+
+
+
       def parameter(attributes)
         if attributes[:in] && attributes[:in].to_sym == :path
           attributes[:required] = true
diff --git a/rswag-specs/lib/rswag/specs/extended_schema.rb b/rswag-specs/lib/rswag/specs/extended_schema.rb
index 62eb4ee..847cd72 100644
--- a/rswag-specs/lib/rswag/specs/extended_schema.rb
+++ b/rswag-specs/lib/rswag/specs/extended_schema.rb
@@ -15,7 +15,7 @@ module Rswag
     class ExtendedTypeAttribute < JSON::Schema::TypeV4Attribute
       
       def self.validate(current_schema, data, fragments, processor, validator, options={})
-        return if data.nil? && current_schema.schema['x-nullable'] == true
+        return if data.nil? && (current_schema.schema['nullable'] == true || current_schema.schema['x-nullable'] == true)
         super
       end
     end
diff --git a/rswag-specs/lib/rswag/specs/request_factory.rb b/rswag-specs/lib/rswag/specs/request_factory.rb
index 7106015..0bb7a33 100644
--- a/rswag-specs/lib/rswag/specs/request_factory.rb
+++ b/rswag-specs/lib/rswag/specs/request_factory.rb
@@ -39,7 +39,7 @@ module Rswag
       def derive_security_params(metadata, swagger_doc)
         requirements = metadata[:operation][:security] || swagger_doc[:security] || []
         scheme_names = requirements.flat_map { |r| r.keys }
-        schemes = (swagger_doc[:securityDefinitions] || {}).slice(*scheme_names).values
+        schemes = (swagger_doc[:components][:securitySchemes] || {}).slice(*scheme_names).values
 
         schemes.map do |scheme|
           param = (scheme[:type] == :apiKey) ? scheme.slice(:name, :in) : { name: 'Authorization', in: :header }
diff --git a/rswag-specs/lib/rswag/specs/response_validator.rb b/rswag-specs/lib/rswag/specs/response_validator.rb
index c3e363f..d2b71ad 100644
--- a/rswag-specs/lib/rswag/specs/response_validator.rb
+++ b/rswag-specs/lib/rswag/specs/response_validator.rb
@@ -41,9 +41,12 @@ module Rswag
         response_schema = metadata[:response][:schema]
         return if response_schema.nil?
 
+        components_schemas = {components: {schemas: swagger_doc[:components][:schemas]}}
+
         validation_schema = response_schema
           .merge('$schema' => 'http://tempuri.org/rswag/specs/extended_schema')
-          .merge(swagger_doc.slice(:definitions))
+          .merge(components_schemas)
+        
         errors = JSON::Validator.fully_validate(validation_schema, body)
         raise UnexpectedResponse, "Expected response body to match schema: #{errors[0]}" if errors.any?
       end
diff --git a/test-app/spec/integration/blogs_spec.rb b/test-app/spec/integration/blogs_spec.rb
index abca570..08297f8 100644
--- a/test-app/spec/integration/blogs_spec.rb
+++ b/test-app/spec/integration/blogs_spec.rb
@@ -10,7 +10,7 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
       operationId 'createBlog'
       consumes 'application/json'
       produces 'application/json'
-      parameter name: :blog, in: :body, schema: { '$ref' => '#/definitions/blog' }
+      parameter name: :blog, in: :body, schema: { '$ref' => '#/components/schemas/blog' }
 
       let(:blog) { { title: 'foo', content: 'bar' } }
 
@@ -19,7 +19,7 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
       end
 
       response '422', 'invalid request' do
-        schema '$ref' => '#/definitions/errors_object'
+        schema '$ref' => '#/components/schemas/errors_object'
 
         let(:blog) { { title: 'foo' } }
         run_test! do |response|
@@ -38,7 +38,7 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
       let(:keywords) { 'foo bar' }
 
       response '200', 'success' do
-        schema type: 'array', items: { '$ref' => '#/definitions/blog' }
+        schema type: 'array', items: { '$ref' => '#/components/schemas/blog' }
       end
 
       response '406', 'unsupported accept header' do
@@ -65,7 +65,7 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
         header 'Last-Modified', type: :string
         header 'Cache-Control', type: :string
 
-        schema '$ref' => '#/definitions/blog'
+        schema '$ref' => '#/components/schemas/blog'
 
         examples 'application/json' => {
             id: 1,
diff --git a/test-app/spec/swagger_helper.rb b/test-app/spec/swagger_helper.rb
index fa1162a..e206999 100644
--- a/test-app/spec/swagger_helper.rb
+++ b/test-app/spec/swagger_helper.rb
@@ -14,47 +14,61 @@ RSpec.configure do |config|
   # the root example_group in your specs, e.g. describe '...', swagger_doc: 'v2/swagger.json'
   config.swagger_docs = {
     'v1/swagger.json' => {
-      swagger: '2.0',
+      openapi: '3.0.0',
       info: {
         title: 'API V1',
         version: 'v1'
       },
       paths: {},
-      definitions: {
-        errors_object: {
-          type: 'object',
-          properties: {
-            errors: { '$ref' => '#/definitions/errors_map' }
+      servers: [
+          {
+              url: "https://{defaultHost}",
+              variables: {
+                  defaultHost: {
+                      default: "www.example.com"
+                  }
+              }
           }
+      ],
+ 
+      components: {
+        schemas: {
+            errors_object: {
+                type: 'object',
+                properties: {
+                    errors: { '$ref' => '#/components/schemas/errors_map' }
+                }
+            },
+            errors_map: {
+                type: 'object',
+                additionalProperties: {
+                    type: 'array',
+                    items: { type: 'string' }
+                }
+            },
+            blog: {
+                type: 'object',
+                properties: {
+                    id: { type: 'integer' },
+                    title: { type: 'string' },
+                    content: { type: 'string', nullable: true },
+                    thumbnail: { type: 'string'}
+                },
+                required: [ 'id', 'title', 'content', 'thumbnail' ]
+            }
         },
-        errors_map: {
-          type: 'object',
-          additionalProperties: {
-            type: 'array',
-            items: { type: 'string' }
-          }
-        },
-        blog: {
-          type: 'object',
-          properties: {
-            id: { type: 'integer' },
-            title: { type: 'string' },
-            content: { type: 'string', 'x-nullable': true },
-            thumbnail: { type: 'string'}
-          },
-          required: [ 'id', 'title', 'content', 'thumbnail' ]
+        securitySchemes: {
+            basic_auth: {
+                type: :http,
+                scheme: :basic
+            },
+            api_key: {
+                type: :apiKey,
+                name: 'api_key',
+                in: :query
+            }
         }
       },
-      securityDefinitions: {
-        basic_auth: {
-          type: :basic
-        },
-        api_key: {
-          type: :apiKey,
-          name: 'api_key',
-          in: :query
-        }
-      }
     }
   }
 end
diff --git a/test-app/swagger/v1/swagger.json b/test-app/swagger/v1/swagger.json
index 8531c7a..6e24e14 100644
--- a/test-app/swagger/v1/swagger.json
+++ b/test-app/swagger/v1/swagger.json
@@ -1,5 +1,5 @@
 {
-  "swagger": "2.0",
+  "openapi": "3.0.0",
   "info": {
     "title": "API V1",
     "version": "v1"
@@ -99,7 +99,7 @@
             "name": "blog",
             "in": "body",
             "schema": {
-              "$ref": "#/definitions/blog"
+              "$ref": "#/components/schemas/blog"
             }
           }
         ],
@@ -110,7 +110,7 @@
           "422": {
             "description": "invalid request",
             "schema": {
-              "$ref": "#/definitions/errors_object"
+              "$ref": "#/components/schemas/errors_object"
             }
           }
         }
@@ -173,7 +173,7 @@
               }
             },
             "schema": {
-              "$ref": "#/definitions/blog"
+              "$ref": "#/components/schemas/blog"
             },
             "examples": {
               "application/json": {
@@ -225,57 +225,70 @@
       }
     }
   },
-  "definitions": {
-    "errors_object": {
-      "type": "object",
-      "properties": {
-        "errors": {
-          "$ref": "#/definitions/errors_map"
+  "servers": [
+    {
+      "url": "https://{defaultHost}",
+      "variables": {
+        "defaultHost": {
+          "default": "www.example.com"
         }
       }
-    },
-    "errors_map": {
-      "type": "object",
-      "additionalProperties": {
-        "type": "array",
-        "items": {
-          "type": "string"
-        }
-      }
-    },
-    "blog": {
-      "type": "object",
-      "properties": {
-        "id": {
-          "type": "integer"
-        },
-        "title": {
-          "type": "string"
-        },
-        "content": {
-          "type": "string",
-          "x-nullable": true
-        },
-        "thumbnail": {
-          "type": "string"
+    }
+  ],
+  "components": {
+    "schemas": {
+      "errors_object": {
+        "type": "object",
+        "properties": {
+          "errors": {
+            "$ref": "#/components/schemas/errors_map"
+          }
         }
       },
-      "required": [
-        "id",
-        "title",
-        "content",
-        "thumbnail"
-      ]
-    }
-  },
-  "securityDefinitions": {
-    "basic_auth": {
-      "type": "basic"
+      "errors_map": {
+        "type": "object",
+        "additionalProperties": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        }
+      },
+      "blog": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "integer"
+          },
+          "title": {
+            "type": "string"
+          },
+          "content": {
+            "type": "string",
+            "nullable": true
+          },
+          "thumbnail": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "id",
+          "title",
+          "content",
+          "thumbnail"
+        ]
+      }
     },
-    "api_key": {
-      "type": "apiKey",
-      "name": "api_key",
-      "in": "query"
+    "securitySchemes": {
+      "basic_auth": {
+        "type": "http",
+        "scheme": "basic"
+      },
+      "api_key": {
+        "type": "apiKey",
+        "name": "api_key",
+        "in": "query"
+      }
     }
   }
 }
\ No newline at end of file