MSW

ELI5 — The Vibe Check

MSW (Mock Service Worker) intercepts your API calls at the network level and returns fake data, like a polite man-in-the-middle attack on yourself. Your app thinks it's talking to a real server, but MSW is backstage feeding it scripted responses. Perfect for testing.

Real Talk

MSW (Mock Service Worker) is an API mocking library that intercepts network requests using a Service Worker in the browser and a custom interceptor in Node.js. It enables realistic API mocking for development, testing, and debugging without modifying application code.

Show Me The Code

http.get('/api/users', () => {
  return HttpResponse.json([
    { id: 1, name: 'John' }
  ]);
});

When You'll Hear This

"MSW lets us develop the frontend before the backend is ready" / "Our tests use MSW so we never hit real APIs"