The fastest way to
mock an API._

You need the API to return something specific. The backend isn't yours to change. Open JediMock, configure the mock, paste one script in DevTools. The next request is intercepted. Nothing else required.

Open JediMock View on GitHub

DevTools — Console

      // script runs once on paste
      ⚡ JediMock active { url: '/api/users/*', target: 'Response', mode: 'Merge' }
      // your app makes a request as normal
      ⚡ JediMock intercepted { url: '/api/users/42', status: 200, delay: '0ms' }
      // test auth flow — 401 on first call, 200 after
      ⚡ JediMock rule matched { rule: 'Call #1', status: 401 }
      ⚡ JediMock rule matched { rule: 'After #1', status: 200 }
      > 
    

No service worker registered in your app. No proxy running on localhost. No HTTPS certificate to install. No Mockoon server to keep running. Just a script you paste once.

It intercepts both fetch and XMLHttpRequest. You can modify the response, the request body, or both — merge your changes on top of the real data or replace it entirely. Wildcards work: /api/users/* catches every user endpoint in one script.

Refresh the page and the mock is gone. The real API comes back. No cleanup, no config to undo.

Everything else

JediMock

Needs a service worker in your app

Zero footprint in your app

Proxy server running locally

Nothing running except your browser

HTTPS certificate setup

Paste a script. Done.

Separate mock server to maintain

Nothing to install or maintain

Modify response OR request, not both

Intercept request + response together

Five tools in one file. Mock generator, JSON editor with bulk operations, validator with accurate line-level errors, diff, beautifier. Session persists across page reloads. Import and export configs. Share a mock via URL. No account needed.

Open JediMock — free

The fastest way to mock an API._

The fastest way to
mock an API._