About API Mock Server

Generate mock API responses from JSON schema with status codes, delays, and realistic data. Part of the DevTools Surf developer suite. Browse more tools in the API / Config collection.

Use Cases

• Unblock frontend development while backend endpoints are still being built
• Reproduce specific API error responses for testing error-handling paths
• Demo a product to stakeholders before the real API is deployed
• Simulate third-party API behavior in integration tests without network calls

Tips

• Define a JSON schema for the response body; the mock server generates realistic synthetic data (names, dates, UUIDs) from it
• Set an artificial delay (in ms) to simulate real network latency for frontend development
• Configure different status codes (200, 404, 500) for different request paths to test error-handling code

Fun Facts

• Mock servers became essential in the mid-2010s with the rise of microservices — when frontend and backend teams work in parallel, mocks let UI development proceed before the real API exists.
• WireMock, one of the most popular open-source mock server libraries, was first released in 2011. Postman added integrated mock servers in 2017, making the feature accessible to non-developers.
• Contract testing (using tools like Pact) emerged as a complement to mocking: instead of each team maintaining separate mocks, consumer-driven contracts let teams verify compatibility automatically.

FAQ

Does the mock server run locally or in the cloud?

The tool generates mock configuration and response definitions you can run locally with WireMock, Mockoon, or json-server. It does not host a live server itself.

Can I generate realistic fake data?

Yes — the schema-based generator uses Faker.js conventions for common field names (email, name, date, uuid). Custom fields use the type hint in the schema.

What is the difference between a mock and a stub?

A stub returns fixed pre-programmed responses. A mock also verifies that the caller made specific calls with expected arguments. This tool generates stubs — verification is the job of your test framework.