Vitest Has a Free Test Runner That Makes Jest Feel Slow

Jest was revolutionary. But it's slow — cold starts take seconds, watch mode re-runs too much, and configuring TypeScript/ESM support feels like solving a puzzle. Vitest runs on Vite and delivers the same API with 10x faster execution. What Vitest Gives You for Free Vite-powered — instant HMR for tests, shared config with your app Jest-compatible API — describe , it , expect , vi.mock() all work TypeScript/ESM native — no ts-jest , no Babel, no config In-source testing — write tests next to your code UI mode — visual test explorer in the browser Code coverage — built-in with c8 or istanbul Benchmark mode — performance testing built in Quick Start npm install -D vitest // package.json { "scripts" : { "test" : "vitest" , "test:ui" : "vitest --ui" , "coverage" : "vitest run --coverage" } } No config file needed if you already use Vite. Vitest reads vite.config.ts automatically. Writing Tests (Familiar Jest API) // math.test.ts import { describe , it , expect } from ' vitest ' ; import { c