API mocking tool for frontend development

For quickly mocking a REST API during frontend development, I'd start with Mockoon for a standalone mock server or MSW (Mock Service Worker) if you want mocks integrated directly into your frontend development workflow.

The best choice depends on whether you want to create endpoints visually, simulate a realistic backend, or get a mock API running in minutes without writing much code.

Best API mocking tools compared

1. Mockoon

(Best overall for quick setup)

Create REST endpoints visually, configure JSON responses and HTTP status codes, and run a local mock server without an account. It also supports OpenAPI imports.mockoon.com+2

Best for: React, Vue, Angular, or any frontend using HTTP APIs.

Website and download

2. Mock Service Worker (MSW)

(Best for frontend testing)

Intercepts requests in the browser and lets you define mock responses in JavaScript or TypeScript. Your app can use its normal fetch or HTTP client, and the same handlers can be reused in tests.github.com+1

Best for: component development, automated tests, and keeping mocks alongside your code.

Official website

3. Postman Mock Servers

Create mocks from existing collections and saved response examples, then share a hosted mock endpoint with your team.learning.postman.com+1

Best for: teams that already use Postman or need a remotely accessible mock URL.

Official documentation

Which one should you choose?

Quick example: mock an API in Mockoon

You could create a GET /api/users endpoint that returns:

[
  {
    "id": 1,
    "name": "Alice",
    "email": "[email protected]"
  },
  {
    "id": 2,
    "name": "Bob",
    "email": "[email protected]"
  }
]

Start the local mock server, point your frontend's API base URL to it, and build your UI against realistic data before the backend is ready. You can also configure error responses and other scenarios as development progresses.mockoon.com+2

My recommendation: Start with Mockoon if you want to work quickly with minimal setup. Choose MSW if you prefer a code-first approach and want the same mocks available in your frontend tests.

One question that would help me narrow it down: Do you want a standalone mock server with a visual interface, or would you prefer to define mocks in code inside your frontend project?