JS Runtimes
3 open source tools compared. Sorted by stars — scroll down for our analysis.
| Tool | Stars | Velocity | Language | License | Score |
|---|---|---|---|---|---|
 Deno Modern runtime for JavaScript and TypeScript | 106.4k | — | Rust | MIT License | 82 |
 Bun Fast JS runtime, bundler, test runner, and package manager | 88.4k | — | Zig | — | 72 |
| 924 | — | Rust | — | 43 |
Our Analysis
Deno is Node.js rebuilt by Node's creator with every lesson learned baked in: TypeScript-first, secure by default, built-in linter, formatter, and test runner. No node_modules. No package.json. Deno 2's npm compatibility finally removed the ecosystem barrier that kept most developers away. Node.js is still the safe production choice with 100% npm compatibility and 15 years of battle-testing. Bun is faster raw — 8ms cold starts vs Deno's 40ms — but with less mature tooling. Deno sits in the middle: not the fastest, not the most compatible, but the most thoughtful runtime design. Use Deno if you care about security (its permission model actually prevents supply-chain attacks from rogue npm packages), want TypeScript without config files, or are building for Deno Deploy's edge network. The catch: 95% npm compatibility means 5% of packages still break, and those are often the obscure native modules your project depends on. The ecosystem is smaller — fewer tutorials, fewer Stack Overflow answers. And in the job market, "Deno experience" is still a rarity.
Bun is the JavaScript runtime that wants to replace everything: Node.js, npm, webpack, and Jest in a single binary. Written in Zig with JavaScriptCore (not V8), it cold-starts in 8-15ms, installs dependencies 20-40x faster than npm, and handles 120k requests/sec in synthetic benchmarks. Node.js is still the production bedrock — 100% npm compatibility, 15 years of institutional knowledge, enterprise LTS support. Deno is the security-conscious alternative with a permission model Bun lacks entirely. But for developer experience, Bun is unmatched: one tool for runtime, package management, bundling, and testing. Use Bun for greenfield projects, serverless functions where cold starts matter, and CI pipelines where 47-second installs beat npm's 28 minutes. The catch: 98% npm compatibility means the 2% that breaks could be your critical dependency — especially native C++ bindings or V8-specific modules. The "Sustainable Use" license has commercial restrictions. And in production with real databases and business logic, the raw speed advantage over Node.js largely disappears.