LLM Best Practices

Bun vs Node.js

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Overview

Use Node.js on a supported LTS line for production services where compatibility and platform support decide; use Bun when one tool for running, installing, bundling, and testing is worth testing your dependencies against it. As of 2026-10-01 Node 26 is Current (released 2026-05-05), Node 24 and 22 are LTS, and Node 20 and 25 are end of life. Bun is at 1.4 (1.4.2 on 2026-09-05); 1.4 was a rewrite from Zig to Rust, and Anthropic acquired Bun on 2025-12-02.

Comparison

DimensionNode.jsBun
RoleRuntime; npm, pnpm, or Yarn for packagesRuntime, package manager, bundler, and test runner in one binary
TypeScriptStrips types by default since 22.18 and 23.6 (stable in 24.12+); no enums, runtime namespaces, or tsconfig.json readingRuns TypeScript directly
Built-in clientsnode: modules; database and S3 clients come from packagesBun.SQL (PostgreSQL, MySQL, SQLite), Bun.redis, Bun.S3Client
HTTPnode:http, node:http2; frameworks on topBun.serve, with HTTP/2 since 1.4.1
CompatibilityReference implementation of Node APIsTargets Node API compatibility (1.4 tracks Node 26.3.0); edge cases remain
WindowsSupportedSupported, including Windows ARM64 in 1.4
Release modelCurrent line plus LTS lines; from Node 27, one major per year and every major becomes LTS with 30 months of supportFrequent minor releases

Pick Node.js when

Pick Node.js for production defaults.

  • Run only supported LTS lines (24 or 22); Node 20 is already end of life.
  • Native addons, vendor SDKs, APM agents, and serverless platforms that document Node first.
  • Teams that need long-term support commitments and the broadest hosting options.
  • On 22.18 and later, simple TypeScript scripts run without a flag; use a build step or tsx for enums, runtime namespaces, or tsconfig paths.

Pick Bun when

Pick Bun when its integrated toolchain is the advantage.

  • Scripts, CLIs, internal tools, and test suites where bun test and bun install replace several dev dependencies.
  • Services that benefit from built-in Postgres, Redis, and S3 clients and Bun.serve.
  • Greenfield projects where you can run your full test suite on Bun in CI before committing.
  • Verify per dependency: run the production workload under Bun, including native modules and AsyncLocalStorage behavior, before switching.

Mix them

Use Bun only as the package manager and script runner while deploying on Node, or the reverse. Run CI on the runtime you deploy, and pin the version in package.json engines or a version file. For package manager trade-offs see yarn-vs-pnpm; for test runners see jest-vs-vitest.

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