Bazel vs Bun

Bazel is a free, open-source tool for automating software builds and tests across languages and platforms. Projects define targets in BUILD files using Starlark, which can also be used to create custom rules and macros. Bazel caches prior work and rebuilds what needs to change, while running tasks in parallel. It supports languages including C++, Java, Kotlin, Python, Go, and Rust, with outputs for desktop, server, Android, and iOS. Bazel runs on Linux, macOS, and Windows, and the documentation describes builds with 100,000 or more source files across multiple repositories. Sandboxing can make builds and tests more hermetic, and failures return a non-zero exit code for basic CI integration. Teams can share outputs through a remote cache, but must select and maintain its backend and secure access because it can contain binaries. IDE options include plugins for IntelliJ, Android Studio, CLion, and Visual Studio Code, plus Xcode integration. Bazel is not well suited to uncached deployment steps that change cloud configuration.

Bun combines a JavaScript runtime, package manager, test runner, and bundler in one binary. It runs JavaScript and TypeScript on JavaScriptCore, with support for Node.js APIs and node_modules. Its npm-compatible package manager supports workspaces, catalogs, overrides, patches, readable lockfiles, private registry authentication, dependency resolution, and offline installation. The test runner includes Jest-compatible expectations, mocks, snapshots, DOM testing, and coverage. For builds, Bun handles TypeScript, JSX, CSS, and HTML for browsers and servers, and includes a development server with hot module reloading and single-file executables. Built-in APIs cover PostgreSQL, MySQL, SQLite, Redis, S3-compatible storage, HTTP, and WebSockets. The project names Next.js, Remix, Nuxt, Astro, SvelteKit, Hono, and Elysia among frameworks that run on Bun. It is MIT-licensed and developed publicly on GitHub. Bun runs on Linux, macOS, and Windows, subject to minimum OS versions and x64 processors with SSE4.2. Install options include an official script, npm, Homebrew, Windows package managers, and Docker. Support and discussion are available through Discord.