MSW Has a Free API That Makes API Mocking in Tests and Dev Actually Work

Mock Service Worker (MSW) intercepts network requests at the service worker level. No monkey-patching fetch. No test-specific HTTP clients. Your code doesn't know it's being mocked. Setup: Define Handlers import { http, HttpResponse } from "msw"; export const handlers = [ // GET request http.get("/api/products", () => { return HttpResponse.json([ { id: 1, title: "Widget", price: 29.99 }, { id: 2, title: "Gadget", price: 49.99 }, ]); }), // POST with request body http.post("/api/products", async ({ request }) => { const body = await request.json(); return HttpResponse.json({ id: 3, ...body }, { status: 201 }); }), // Dynamic params http.get("/api/products/:id", ({ params }) => { return HttpResponse.json({ id: params.id, title: "Product" }); }), // Query parameters http.get("/api/search", ({ request }) => { const url = new URL(request.url); const query = url.searchParams.get("q"); return HttpResponse.json({ results: [], query }); }), // Error responses http.delete("/api/produ