API Response Mocker - Generate Realistic Test Data

API mocking simulates backend API responses without requiring a real server. It's crucial for frontend development, testing, and prototyping because it allows developers to work independently, test edge cases, and develop faster without waiting for backend completion.

Dynamic placeholders are replaced with realistic data when you generate a preview. Use {{uuid}} for unique IDs, {{now}} for timestamps, and {{faker.*}} for Faker.js methods. For example, {{faker.internet.email()}} generates a random email address. These placeholders help create realistic test data without manual input.

HTTP/1.1 is the traditional protocol with simple request-response. HTTP/2 adds multiplexing, server push, and header compression for better performance. HTTP/3 uses QUIC protocol over UDP for even faster connections and better reliability on unreliable networks. Choose based on your testing requirements.

Absolutely! The tool includes templates for various error scenarios: 404 Not Found, 500 Server Error, 401 Unauthorized, 422 Validation Errors, and 429 Rate Limiting. Testing error responses is essential for building robust applications that handle failures gracefully.

After generating a preview, you can copy the JSON response or copy a cURL command. The cURL command is a template: set BASE_URL to the server that serves the endpoint (this tool does not host one), then share it with team members or use it in automated testing scripts.

Test both success and error scenarios, use realistic data volumes, test pagination and edge cases (empty results, single items), validate response times with the delay feature, test different HTTP status codes, and ensure your frontend handles all response types correctly.