diff --git a/.github/ISSUE_TEMPLATE/apiary.yml b/.github/ISSUE_TEMPLATE/doc.yml
similarity index 94%
rename from .github/ISSUE_TEMPLATE/apiary.yml
rename to .github/ISSUE_TEMPLATE/doc.yml
index fcf5f7c..34b70c2 100644
--- a/.github/ISSUE_TEMPLATE/apiary.yml
+++ b/.github/ISSUE_TEMPLATE/doc.yml
@@ -1,6 +1,6 @@
-name: Apiary
+name: WS API documentation
 description: Issue about documentation for ThePay.cz WS API
-labels: ["Apiary"]
+labels: ["OpenAPI"]
 body:
   - type: markdown
     attributes:
diff --git a/.github/ISSUE_TEMPLATE/sdk.yml b/.github/ISSUE_TEMPLATE/sdk.yml
index cf7bce6..4154518 100644
--- a/.github/ISSUE_TEMPLATE/sdk.yml
+++ b/.github/ISSUE_TEMPLATE/sdk.yml
@@ -20,8 +20,7 @@ body:
       options:
         - Production
         - Demo
-        - Apiary mock
-        - Apiary proxy
+        - OpenAPI mock
     validations:
       required: false
   - type: input
diff --git a/.github/ISSUE_TEMPLATE/ws.yml b/.github/ISSUE_TEMPLATE/ws.yml
index 7f7287b..6ed156a 100644
--- a/.github/ISSUE_TEMPLATE/ws.yml
+++ b/.github/ISSUE_TEMPLATE/ws.yml
@@ -20,8 +20,7 @@ body:
       options:
         - Production
         - Demo
-        - Apiary mock
-        - Apiary proxy
+        - OpenAPI mock
     validations:
       required: true
   - type: input
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a6d3c1f..8ab8d12 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,6 +10,11 @@ jobs:
         name: "php 8.4"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.4"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             -   name: Checkout repository
                 uses: actions/checkout@v4
@@ -20,6 +25,9 @@ jobs:
             -   name: Run static analysis
                 run: composer stan
 
+            -   name: Create mock server from our production OpenAPI
+                run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             -   name: Run tests
                 run: composer test
 
@@ -27,6 +35,11 @@ jobs:
         name: "php 8.3"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.3"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             -   name: Checkout repository
                 uses: actions/checkout@v4
@@ -37,6 +50,9 @@ jobs:
             -   name: Run static analysis
                 run: composer stan
 
+            -   name: Create mock server from our production OpenAPI
+                run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             -   name: Run tests
                 run: composer test
 
@@ -44,6 +60,11 @@ jobs:
         name: "php 8.2 psr/http-message 2.0"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.2"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             -   name: Checkout repository
                 uses: actions/checkout@v3
@@ -57,6 +78,9 @@ jobs:
             -   name: Run static analysis
                 run: composer stan
 
+            -   name: Create mock server from our production OpenAPI
+                run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             -   name: Run tests
                 run: composer test
 
@@ -64,6 +88,11 @@ jobs:
         name: "php 8.2 psr/http-message 1.0"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.2"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             -   name: Checkout repository
                 uses: actions/checkout@v3
@@ -74,6 +103,9 @@ jobs:
             -   name: Run static analysis
                 run: composer stan
 
+            -   name: Create mock server from our production OpenAPI
+                run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             -   name: Run tests
                 run: composer test
 
@@ -81,6 +113,11 @@ jobs:
         name: "php 8.1"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.1"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             - name: Checkout repository
               uses: actions/checkout@v3
@@ -91,6 +128,9 @@ jobs:
             - name: Run static analysis
               run: composer stan
 
+            - name: Create mock server from our production OpenAPI
+              run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             - name: Run tests
               run: composer test
 
@@ -98,6 +138,11 @@ jobs:
         name: "php 8.0"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:8.0"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             - name: Checkout repository
               uses: actions/checkout@v3
@@ -108,6 +153,9 @@ jobs:
             - name: Run static analysis
               run: composer stan
 
+            - name: Create mock server from our production OpenAPI
+              run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             - name: Run tests
               run: composer test
 
@@ -115,6 +163,11 @@ jobs:
         name: "php 7.4"
         runs-on: ubuntu-latest
         container: "nofutur3/php-tests:7.4"
+        services:
+            openAPImock:
+                image: mockserver/mockserver
+                ports:
+                    - 1080:1080
         steps:
             # Deprecation example for future support removal.
             #
@@ -130,6 +183,9 @@ jobs:
             -   name: Run static analysis
                 run: composer stan
 
+            -   name: Create mock server from our production OpenAPI
+                run: curl -X PUT -d "{\"specUrlOrPayload\":\"https://gate.thepay.cz/openapi.yaml\"}" http://openAPImock:1080/mockserver/openapi
+
             -   name: Run tests
                 run: composer test
 
diff --git a/tests/BaseTestCase.php b/tests/BaseTestCase.php
index 085888e..293e5a3 100644
--- a/tests/BaseTestCase.php
+++ b/tests/BaseTestCase.php
@@ -9,8 +9,8 @@
 use PHPUnit\Framework\TestCase;
 use ThePay\ApiClient\Service\ApiService;
 use ThePay\ApiClient\Service\SignatureService;
+use ThePay\ApiClient\Tests\Mocks\TheConfig;
 use ThePay\ApiClient\TheClient;
-use ThePay\ApiClient\TheConfig;
 
 abstract class BaseTestCase extends TestCase
 {
@@ -22,21 +22,15 @@ protected function setUp(): void
     {
         parent::setUp();
 
-        $this->config = new TheConfig(self::MERCHANT_ID, 1, 'password', 'https://test.api.cz/', 'https://test.gate.cz/');
+        $this->config = new TheConfig();
     }
 
     /**
-     * method return TheClient witch use apiary mock server
+     * method return TheClient witch use mock server
      */
-    protected function getApiaryClient(): TheClient
+    protected function getMockClient(): TheClient
     {
-        $config = new TheConfig(
-            '6cdf1b24',
-            1212,
-            'password',
-            'https://private-aa6aa3-thepay.apiary-mock.com/',
-            'https://private-ddc40-gatezalozeniplatby.apiary-mock.com/'
-        );
+        $config = new TheConfig();
 
         $httpFactory = new HttpFactory();
 
diff --git a/tests/CancelPreauthorizationPaymentTest.php b/tests/CancelPreauthorizationPaymentTest.php
index e7f8d73..a48f62e 100644
--- a/tests/CancelPreauthorizationPaymentTest.php
+++ b/tests/CancelPreauthorizationPaymentTest.php
@@ -4,71 +4,29 @@
 
 namespace ThePay\ApiClient\Tests;
 
-use GuzzleHttp\Psr7\HttpFactory;
-use GuzzleHttp\Psr7\Response;
-use PHPUnit\Framework\MockObject\MockObject;
-use Psr\Http\Client\ClientInterface;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
-use ThePay\ApiClient\Service\ApiService;
-use ThePay\ApiClient\Service\SignatureService;
 use ThePay\ApiClient\TheClient;
 
 final class CancelPreauthorizationPaymentTest extends BaseTestCase
 {
-    /** @var MockObject&ClientInterface */
-    private MockObject $httpClient;
     private TheClient $client;
 
     protected function setUp(): void
     {
         parent::setUp();
-        $this->httpClient = $this->createMock(ClientInterface::class);
-        $httpFactory = new HttpFactory();
-        $apiService = new ApiService(
-            $this->config,
-            $this->createMock(SignatureService::class),
-            $this->httpClient,
-            $httpFactory,
-            $httpFactory
-        );
-        $this->client = new TheClient($this->config, $apiService);
+        $this->client = $this->getMockClient();
     }
 
     public function testRequest(): void
     {
-        $this->httpClient
-            ->expects(self::once())
-            ->method('sendRequest')
-            ->willReturnCallback(function (RequestInterface $request): ResponseInterface {
-                $expectedUrl = $this->config->getApiUrl() . 'projects/1/payments/abc/preauthorized?merchant_id=' . self::MERCHANT_ID;
-
-                self::assertSame('DELETE', $request->getMethod());
-                self::assertSame($expectedUrl, $request->getUri()->__toString());
-
-                return $this->getOkResponse();
-            })
-        ;
-
         $this->client->cancelPreauthorizedPayment('abc');
+        self::assertTrue(true);
     }
 
     public function testNotOkResponse(): void
     {
         $this->expectException(\Exception::class);
 
-        $this->httpClient->method('sendRequest')->willReturn($this->getNotOkResponse());
-
-        $this->client->cancelPreauthorizedPayment('abc');
-    }
-
-    private function getOkResponse(): ResponseInterface
-    {
-        return new Response(204);
-    }
-
-    private function getNotOkResponse(): ResponseInterface
-    {
-        return new Response(401);
+        /** @phpstan-ignore-next-line */
+        $this->client->cancelPreauthorizedPayment('');
     }
 }
diff --git a/tests/GeneratePaymentConfirmationTest.php b/tests/GeneratePaymentConfirmationTest.php
index 4f58833..0ca186d 100644
--- a/tests/GeneratePaymentConfirmationTest.php
+++ b/tests/GeneratePaymentConfirmationTest.php
@@ -4,70 +4,24 @@
 
 namespace ThePay\ApiClient\Tests;
 
-use GuzzleHttp\Psr7\HttpFactory;
-use GuzzleHttp\Psr7\Response;
-use Psr\Http\Client\ClientInterface;
-use Psr\Http\Message\RequestInterface;
-use ThePay\ApiClient\Service\ApiService;
-use ThePay\ApiClient\Service\SignatureService;
-use ThePay\ApiClient\TheClient;
-
 final class GeneratePaymentConfirmationTest extends BaseTestCase
 {
     public function testSuccess(): void
     {
-        $httpFactory = new HttpFactory();
-
-        $httpClient = $this->createMock(ClientInterface::class);
-        $httpClient->expects(self::once())->method('sendRequest')
-            ->willReturnCallback(function (RequestInterface $request): Response {
-                self::assertSame('GET', $request->getMethod());
-                self::assertSame(
-                    $this->config->getApiUrl() . 'projects/1/payments/testUID/generate_confirmation?language=cs&merchant_id=' . self::MERCHANT_ID,
-                    $request->getUri()->__toString()
-                );
-
-                return new Response(200, [], 'test pdf content');
-            })
-        ;
-
-        $theClient = new TheClient(
-            $this->config,
-            new ApiService(
-                $this->config,
-                $this->createMock(SignatureService::class),
-                $httpClient,
-                $httpFactory,
-                $httpFactory
-            )
-        );
+        $theClient = $this->getMockClient();
 
         $pdfContent = $theClient->generatePaymentConfirmationPdf('testUID', 'cs');
 
-        self::assertSame('test pdf content', $pdfContent);
+        self::assertTrue(is_string($pdfContent));
     }
 
     public function testFailed(): void
     {
-        $httpFactory = new HttpFactory();
-
-        $httpClient = $this->createMock(ClientInterface::class);
-        $httpClient->expects(self::once())->method('sendRequest')
-            ->willReturn(new Response(400));
-
-        $theClient = new TheClient(
-            $this->config,
-            new ApiService(
-                $this->config,
-                $this->createMock(SignatureService::class),
-                $httpClient,
-                $httpFactory,
-                $httpFactory
-            )
-        );
+        $theClient = $this->getMockClient();
 
-        $this->expectException(\RuntimeException::class);
+        $this->expectException(\InvalidArgumentException::class);
 
-        $theClient->generatePaymentConfirmationPdf('testUID', 'cs');
+        /** @phpstan-ignore-next-line */
+        $theClient->generatePaymentConfirmationPdf('');
     }
 }
diff --git a/tests/GetAccountsBalancesTest.php b/tests/GetAccountsBalancesTest.php
index b614098..76d91ab 100644
--- a/tests/GetAccountsBalancesTest.php
+++ b/tests/GetAccountsBalancesTest.php
@@ -4,63 +4,21 @@
 
 namespace ThePay\ApiClient\Tests;
 
-use GuzzleHttp\Psr7\HttpFactory;
-use GuzzleHttp\Psr7\Response;
-use Psr\Http\Client\ClientInterface;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
 use ThePay\ApiClient\Model\AccountBalance;
-use ThePay\ApiClient\Service\ApiService;
-use ThePay\ApiClient\Service\SignatureService;
-use ThePay\ApiClient\TheClient;
 
 final class GetAccountsBalancesTest extends BaseTestCase
 {
     public function test(): void
     {
-        $httpClient = $this->createMock(ClientInterface::class);
-        $httpClient
-            ->expects(self::once())
-            ->method('sendRequest')
-            ->willReturnCallback(function (RequestInterface $request): ResponseInterface {
-                $expectedUrl = $this->config->getApiUrl() . 'balances?account_iban=TP7811112150822790787055&project_id=1&balance_at=2023-03-14T15%3A08%3A44%2B00%3A00&merchant_id=' . self::MERCHANT_ID;
-
-                self::assertSame('GET', $request->getMethod());
-                self::assertSame($expectedUrl, $request->getUri()->__toString());
-
-                return new Response(
-                    200,
-                    [],
-                    '[
-                        {
-                            "iban": "TP7811112150822790787055",
-                            "name": "Test",
-                            "balance": {
-                                "CZK": "45899",
-                                "EUR": "500"
-                            }
-                        }
-                    ]'
-                );
-            });
-
-        $httpFactory = new HttpFactory();
-        $apiService = new ApiService(
-            $this->config,
-            $this->createMock(SignatureService::class),
-            $httpClient,
-            $httpFactory,
-            $httpFactory
-        );
-        $client = new TheClient($this->config, $apiService);
+        $client = $this->getMockClient();
 
         $balances = $client->getAccountsBalances('TP7811112150822790787055', 1, new \DateTime('2023-03-14 15:08:44+00:00'));
         self::assertEquals(
             [
                 new AccountBalance(
                     'TP7811112150822790787055',
-                    'Test',
-                    ['CZK' => '45899', 'EUR' => '500']
+                    'Account #1',
+                    ['CZK' => '1256', 'EUR' => '231', 'USD' => '0']
                 ),
             ],
             $balances
diff --git a/tests/InvalidatePaymentTest.php b/tests/InvalidatePaymentTest.php
index d897f58..0ea7877 100644
--- a/tests/InvalidatePaymentTest.php
+++ b/tests/InvalidatePaymentTest.php
@@ -4,71 +4,29 @@
 
 namespace ThePay\ApiClient\Tests;
 
-use GuzzleHttp\Psr7\HttpFactory;
-use GuzzleHttp\Psr7\Response;
-use PHPUnit\Framework\MockObject\MockObject;
-use Psr\Http\Client\ClientInterface;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
-use ThePay\ApiClient\Service\ApiService;
-use ThePay\ApiClient\Service\SignatureService;
 use ThePay\ApiClient\TheClient;
 
 final class InvalidatePaymentTest extends BaseTestCase
 {
-    /** @var MockObject&ClientInterface */
-    private MockObject $httpClient;
     private TheClient $client;
 
     protected function setUp(): void
     {
         parent::setUp();
-        $this->httpClient = $this->createMock(ClientInterface::class);
-        $httpFactory = new HttpFactory();
-        $apiService = new ApiService(
-            $this->config,
-            $this->createMock(SignatureService::class),
-            $this->httpClient,
-            $httpFactory,
-            $httpFactory
-        );
-        $this->client = new TheClient($this->config, $apiService);
+        $this->client = $this->getMockClient();
     }
 
     public function testRequest(): void
     {
-        $this->httpClient
-            ->expects(self::once())
-            ->method('sendRequest')
-            ->willReturnCallback(function (RequestInterface $request): ResponseInterface {
-                $expectedUrl = $this->config->getApiUrl() . 'projects/1/payments/abc/invalidate?merchant_id=' . self::MERCHANT_ID;
-
-                self::assertSame('PUT', $request->getMethod());
-                self::assertSame($expectedUrl, $request->getUri()->__toString());
-
-                return $this->getOkResponse();
-            })
-        ;
-
         $this->client->invalidatePayment('abc');
+
+        self::assertTrue(true);
     }
 
     public function testNotOkResponse(): void
     {
         $this->expectException(\Exception::class);
 
-        $this->httpClient->method('sendRequest')->willReturn($this->getNotOkResponse());
-
-        $this->client->invalidatePayment('abdc');
-    }
-
-    private function getOkResponse(): ResponseInterface
-    {
-        return new Response(200);
-    }
-
-    private function getNotOkResponse(): ResponseInterface
-    {
-        return new Response(404);
+        $this->client->invalidatePayment('');
     }
 }
diff --git a/tests/Mocks/TheConfig.php b/tests/Mocks/TheConfig.php
new file mode 100644
index 0000000..d9eeee4
--- /dev/null
+++ b/tests/Mocks/TheConfig.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace ThePay\ApiClient\Tests\Mocks;
+
+use ThePay\ApiClient\Tests\BaseTestCase;
+
+class TheConfig extends \ThePay\ApiClient\TheConfig
+{
+    public function __construct()
+    {
+        parent::__construct(
+            BaseTestCase::MERCHANT_ID,
+            1,
+            'password',
+            'https://secure-url/',
+            'https://private-ddc40-gatezalozeniplatby.apiary-mock.com/'
+        );
+    }
+
+    /**
+     * @param non-empty-string|null $specificVersion
+     */
+    public function getApiUrl(?string $specificVersion = null): string
+    {
+        if ($specificVersion !== null) {
+            return 'http://openAPImock:1080/' . $specificVersion . '/';
+        }
+        return 'http://openAPImock:1080/v1/';
+    }
+}
diff --git a/tests/PaymentMethodsTest.php b/tests/PaymentMethodsTest.php
index d73d3bc..a855473 100644
--- a/tests/PaymentMethodsTest.php
+++ b/tests/PaymentMethodsTest.php
@@ -195,7 +195,7 @@ protected function setUp(): void
 
     public function testGettingActivePaymentMethods(): void
     {
-        $client = $this->getApiaryClient();
+        $client = $this->getMockClient();
 
         $methods = $client->getActivePaymentMethods();
         $cardMethod = $methods->get('card');
diff --git a/tests/RealizePreauthorizationPaymentTest.php b/tests/RealizePreauthorizationPaymentTest.php
index 8ce22b8..7bf9112 100644
--- a/tests/RealizePreauthorizationPaymentTest.php
+++ b/tests/RealizePreauthorizationPaymentTest.php
@@ -4,22 +4,12 @@
 
 namespace ThePay\ApiClient\Tests;
 
-use GuzzleHttp\Psr7\HttpFactory;
-use GuzzleHttp\Psr7\Response;
-use PHPUnit\Framework\MockObject\MockObject;
-use Psr\Http\Client\ClientInterface;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
 use ThePay\ApiClient\Model\RealizePreauthorizedPaymentParams;
 use ThePay\ApiClient\Model\RealizePreauthorizedPaymentResult;
-use ThePay\ApiClient\Service\ApiService;
-use ThePay\ApiClient\Service\SignatureService;
 use ThePay\ApiClient\TheClient;
 
 final class RealizePreauthorizationPaymentTest extends BaseTestCase
 {
-    /** @var MockObject&ClientInterface */
-    private MockObject $httpClient;
     private TheClient $client;
 
     /**
@@ -28,36 +18,12 @@ final class RealizePreauthorizationPaymentTest extends BaseTestCase
     protected function setUp(): void
     {
         parent::setUp();
-
-        $this->httpClient = $this->createMock(ClientInterface::class);
-        $httpFactory = new HttpFactory();
-        $apiService = new ApiService(
-            $this->config,
-            $this->createMock(SignatureService::class),
-            $this->httpClient,
-            $httpFactory,
-            $httpFactory
-        );
-        $this->client = new TheClient($this->config, $apiService);
+        $this->client = $this->getMockClient();
     }
 
     public function testRequest(): void
     {
-        $this->httpClient
-            ->expects(self::once())
-            ->method('sendRequest')
-            ->willReturnCallback(function (RequestInterface $request): ResponseInterface {
-                $expectedUrl = $this->config->getApiUrl('v2') . 'projects/1/payments/abc/preauthorized?merchant_id=' . self::MERCHANT_ID;
-
-                self::assertSame('POST', $request->getMethod());
-                self::assertSame($expectedUrl, $request->getUri()->__toString());
-                self::assertSame('{"amount":100}', $request->getBody()->getContents());
-
-                return $this->getOkResponse();
-            })
-        ;
-
-        $response = $this->client->realizePreauthorizedPayment(new RealizePreauthorizedPaymentParams(100, 'abc'));
+        $response = $this->client->realizePreauthorizedPayment(new RealizePreauthorizedPaymentParams(9945, 'efd7d8e6-2fa3-3c46-b475-51762331bf56'));
 
         self::assertInstanceOf(RealizePreauthorizedPaymentResult::class, $response);
         self::assertSame(RealizePreauthorizedPaymentResult::STATE_PAID, $response->getState());
@@ -67,18 +33,6 @@ public function testNotOkResponse(): void
     {
         $this->expectException(\Exception::class);
 
-        $this->httpClient->method('sendRequest')->willReturn($this->getNotOkResponse());
-
-        $this->client->realizePreauthorizedPayment(new RealizePreauthorizedPaymentParams(100, 'abc'));
-    }
-
-    private function getOkResponse(): ResponseInterface
-    {
-        return new Response(200, [], '{"state":"paid"}');
-    }
-
-    private function getNotOkResponse(): ResponseInterface
-    {
-        return new Response(401);
+        $this->client->realizePreauthorizedPayment(new RealizePreauthorizedPaymentParams(100, ''));
     }
 }