Shipping without tests is gambling. The 10 open-source testing and automation frameworks below are ranked by GitHub stars (fetched 2026-08-17) — end-to-end, unit, API and load testing. Each links to its repository.
Pick by layer: Playwright/Cypress/Selenium for the browser, pytest/Jest/Vitest for units, and k6 for load — wire them into CI so regressions surface early.
Star count is a popularity signal, not a quality score. Before you commit to one, weigh the things a ranking cannot show: how actively issues are answered, whether the last release was recent enough to trust with your runtime, how heavy the dependency tree is, and whether the API is stable enough that an upgrade will not rewrite your suite. A framework that is slightly less popular but well maintained and predictable will cost you less over a year than one you have to fight. It also pays to keep the layers independent, because a unit runner and a browser driver solve different problems and rarely need to be chosen together.
