uuid

uuid is the de facto standard library for generating RFC9562 (formerly RFC4122) compliant UUIDs in JavaScript and TypeScript. It supports all major UUID versions — v1, v3, v4, v5, v6, and v7 — along with parsing, stringifying, and validation utilities, and ships as a zero-dependency, tree-shakable package that runs identically in Node.js, browsers, and React Native/Expo.

With hundreds of millions of weekly downloads, uuid is one of the most widely used packages in the npm ecosystem, trusted by countless libraries and applications that need collision-resistant unique identifiers for database keys, distributed systems, session tokens, and more.

What You Get

• All RFC9562 UUID versions — v1 (timestamp), v3/v5 (namespace-based), v4 (random), v6/v7 (sortable timestamp) — in one package
• Zero runtime dependencies and full tree-shaking support for minimal bundle size
• Cross-platform support for Node.js, browsers (Chrome/Safari/Firefox/Edge), and React Native/Expo
• A command-line uuid utility for generating IDs from the terminal
• TypeScript types included out of the box, with parse/stringify helpers for working with raw UUID bytes

Common Use Cases

• Generating primary keys for database records without a central ID authority
• Creating unique session, request, or correlation IDs for distributed tracing
• Producing deterministic namespaced IDs (v5) for content-addressable identifiers
• Generating sortable, timestamp-ordered IDs (v7) for high-write database indexes

Under The Hood

Architecture uuid is organized as one small, focused module per concern: each UUID version (v1.ts, v3.ts, v4.ts, v5.ts, v6.ts, v7.ts) lives in its own file and shares common primitives from rng.ts (entropy via crypto.getRandomValues), stringify.ts/parse.ts (byte-array <-> string conversion), and validate.ts (regex-based format checking), all re-exported from a single src/index.ts barrel. Version-specific logic is kept deliberately thin — for example v4.ts fast-paths to the native crypto.randomUUID() when no options or buffer are supplied, falling back to a manually-assembled byte array otherwise — so the library adds almost no overhead over the platform primitives it wraps.

Tech Stack The package is written in TypeScript and compiled to dual ESM/CommonJS-free output (CommonJS support was dropped at v12), targeting native crypto APIs in both Node.js and browsers rather than any userland polyfill. It has zero runtime dependencies; devDependencies are limited to build and quality tooling (TypeScript, Biome for lint/format, Jest and Node’s built-in test runner, WebdriverIO for cross-browser testing, and release-please for versioned releases), keeping the installed footprint of the published package minimal.

Code Quality The src/test directory holds a dedicated spec file for nearly every module (v1, v4, v6, v7, parse, stringify, validate, version, rng, v35), and the maintainers additionally exercise the library end-to-end via examples/ projects covering Node ESM, Jest, TypeScript, and multiple browser bundlers (Rollup, Webpack). Source files are short, single-purpose, and typed throughout, with inline comments flagging performance-sensitive code paths (e.g. the hand-tuned hex-lookup table in stringify.ts) that intentionally trade some readability for measured speed gains.

API Design The public API is extremely low-friction: importing a single named function per UUID version (v4(), v5(), etc.) and calling it with no arguments returns a valid UUID string, with optional parameters available for advanced use (custom entropy, writing into an existing buffer). Naming is consistent across the whole surface (parse/stringify, v1ToV6/v6ToV1, validate/version), and the README documents every export with a runnable example, so getting from npm install to a working UUID takes two lines of code.