vitest/docs/guide/ui.md

Vitest UI

Powered by Vite, Vitest also has a dev server under the hood when running the tests. This allows Vitest to provide a beautiful UI to view and interactive with your tests. The Vitest UI is optional, you can install it by:

npm i -D @vitest/ui

Then you can start the tests with UI by passing the --ui flag:

vitest --ui

Then you can visit the Vitest UI at http://localhost:51204/__vitest__/