The Quick Takeaway

Bun is faster and more compatible with the Node.js ecosystem. Deno has better security and a unique edge deployment story. If performance and compatibility are your priorities, Bun wins. If security and edge computing matter more, Deno is the better choice.

Performance

Bun is the fastest JavaScript runtime available. Built on JavaScriptCore (Safari’s engine), it consistently outperforms both Deno and Node.js in benchmarks. Startup time, HTTP throughput, and file operations are all faster.

Compatibility

Bun’s Node.js compatibility is near-complete. Most npm packages work without modification. Deno 2 improved npm support significantly, but Bun’s compatibility layer is more thorough — especially for packages that use Node.js internals.

Security

Deno’s permission-based security model is unique. Scripts run in a sandbox by default, requiring explicit permission for file system, network, and environment access. Bun has no equivalent sandbox — it runs with full system access like Node.js.

Ecosystem

Deno Deploy provides a unique edge deployment platform — deploy globally in seconds with built-in KV storage and cron jobs. Bun doesn’t have an equivalent hosted platform, though it works with any Node.js hosting.

The Verdict

Choose Bun if you want maximum performance, Node.js compatibility, or built-in bundling/testing. Choose Deno if you need sandboxed execution, edge deployment, or TypeScript-first development.