A list of amazing and awesome open sourced and free tools that powers a good portion of Microsoft products that are rely on JavaScript.

• TypeScript - Typed JavaScript at any scale
• API Extractor - Enforce API surface for libraries, create d.ts rollups, graduate unstable APIs, creates nicely formatted API documentation, and more

• Midgard Yarn - yarn v1, but faster for Azure DevOps feeds
• Midgard Yarn Strict - midgard-yarn, but enforces strictness avoiding phantom dependencies

• Rush - all-in-one styled monorepo manager

• Just - A sensible set of task to build, test, and lint your frontend projects
• Heft - Heft is an extensible build system designed for use with the Rush Stack family of tools

• Rush - all-in-one styled monorepo manager (supports incremental builds, scopes)
• Lage - Run npm scripts in topological order incrementally with cloud cache (supports incremental builds, scopes, cloud cache, pipelining)
• BuildXL (npm) - distributed build runner (works with rush or lage repos)

• Playwright - enables reliable end-to-end testing for modern web apps (works on all modern browsers)
• Flamegrill - scenario level test automation that generates a V8-level sample-based flamegraphs

• Rush - all-in-one styled monorepo manager (requires repo managed by Rush)
• Beachball - makes automating npm publishing a breeze (works for any workspace implementation: yarn, npm v7, pnpm, rush)

• Boll - repository wide linter, enforces standards across all packages inside a monorepo

• workspace-tools - A collection of tools that are useful in a git-controlled monorepo
• p-graph - Run a promise graph with concurrency control.
• @microsoft/task-scheduler - Run a sequence of steps across all the packages of a monorepo
• Rush - contains many useful libraries like command line parsing, incremental build engine using git hashes, useful webpack plugins etc.
• Monaco Editor - code editor that powers Visual Studio Code
• Rooster Editor | demo - framework agnostic rich text editor that powers Outlook

• React Native Windows - cross platform JS development with React Native (Windows)
• React Native MacOS - cross platform JS development with React Native (MacOS)