Developer ToolsMockoon
The fastest way to design and run mock REST APIs locally — free, open source, and offline-first
Developer Tools
Developer ToolsPlaywright
Microsoft's open-source framework for reliable end-to-end testing across Chromium, Firefox, and WebKit — with first-class AI agent support
Developer ToolsMailpit
A small, fast, zero-dependency SMTP and email testing tool with a modern web UI and REST API
Developer ToolsCypress
JavaScript E2E testing with time-travel and Test Replay
Developer ToolsStorybook
Industry-standard frontend workshop for building, documenting and testing React, Vue, Svelte, Angular and React Native components in isolation.
Developer ToolsVitest
The Vite-native testing framework — Jest-compatible API, ESM-first, with built-in browser mode, watch and UI.