Mockingbird

Mock API responses while you build your frontend, with real HTTP status codes (a 500 is a 500) and simulated network failures.

Mockingbird intercepts the calls your app makes and answers them itself — no proxy, no changes to a single line of your code. ▍The difference: real HTTP status codes Most mocking extensions rewrite the response body but leave the status at 200. Your error handling never runs, so you cannot test it. Mockingbird returns the status you configure, for real: • fetch resolves with response.ok === false and response.status === 500 • XMLHttpRequest ends with xhr.status === 500 • axios rejects with error.response.status === 500 • Angular HttpClient emits an HttpErrorResponse with status 500 ▍Network failures, not just HTTP errors It can also simulate a request that never arrives: fetch rejects with a TypeError, XHR fires error with status 0, and axios lands in catch with no error.response. It is the only way to properly test your offline screens. ▍Scenarios Group rules into scenarios ("expired login", "backend down", "everything slow") and switch them on separately. Several can be active at once: their rules add up and the first match wins. ▍Also • Per-rule delay, to test spinners and timeouts • Glob or regular expression patterns, with a built-in tester • Side panel editor, so the page you are testing stays visible • Live log of everything Mockingbird answers • Import and export your setup as JSON to share it with your team Everything runs in your browser. Mockingbird sends nothing to any server.