Bun DocsCompare with Node.js and Deno
Choose a runtime by engine, TypeScript support, package management, permission model, and deployment shape
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Answer the selection question first
All three runtimes execute modern JavaScript. The differences that matter are compatibility boundaries, permission models, package ecosystems, and deployment shapes — not "who is faster." Microbenchmark rankings should never drive the decision; your dependency tree, deployment platform, and team experience should.
Capability matrix
| Dimension | Bun | Node.js | Deno |
|---|---|---|---|
| JS engine | JavaScriptCore | V8 | V8 |
| TypeScript execution | Native, zero config | Experimental since 22.6; erasable syntax runs by default since 23.6, enum etc. still need a transform flag | Native, zero config |
| Type checking | Not included; keep tsc | Not included; keep tsc | Built-in deno check |
| Package management | bun install + text bun.lock | npm + package-lock.json (or pnpm/Yarn) | deno add + deno.lock; JSR registry and npm: specifiers |
node_modules | Required | Required | Not by default (global cache) |
| Node API compatibility | Implements most node: APIs and Node-API; verify edges | Native | Deno 2 covers most node: / npm:; verify edges |
| Permission model | No built-in sandbox | Experimental permission model (--allow-fs-read, etc.) | Sandboxed by default with explicit --allow-* / --deny-* |
| Tests | bun test (Jest-style) | node:test | deno test |
| Bundling | bun build | Not built in (esbuild/tsup, etc.) | No general bundler (deno compile targets executables) |
| Single-file executable | bun build --compile | SEA (more steps) | deno compile |
Volatile rows: check primary sources
Node.js TypeScript support and permissions, and Deno's npm compatibility, are all moving fast. Reviewed on 2026-08-02; confirm against the Node.js docs and Deno docs before writing this into a decision record.
Decision paths
| Your constraint | Lean toward |
|---|---|
| Greenfield CLI or internal service wanting one toolchain and native TS | Bun |
| Production system with heavy native addons requiring LTS and maximum compatibility | Node.js |
| Default-deny sandbox, URL imports, minimal edge scripting | Deno |
| Targeting Cloudflare Workers / Deno Deploy style edge platforms | The platform runtime decides, not local preference |
| Existing large repository | Validate in parallel per Migrate from Node.js; don't switch on faith |
Three common misjudgments
- "Bun is Node-compatible, so no testing needed": native addons, edge-case loaders, and diagnostic tooling can all behave differently — verify each.
- "Deno can't use npm packages": Deno 2's
npm:support covers most common packages, but edges need testing just like Bun. - "Node can't run TypeScript": current Node runs erasable type syntax directly; the real question — who runs type checks and production builds — is identical across all three runtimes.
Constraint wording for agents
Runtime: Bun 1.3.14. Do not suggest Deno permission flags or npm-only workflows.
If a dependency is documented Node-only or Deno-only, stop and report before migrating it.Official references: Bun Node.js compatibility, Node.js TypeScript support, Deno runtime.