Tech Comparisons
UUID vs NanoID
UUID is the established standard for unique identifiers. NanoID is a smaller, faster, URL-safe alternative gaining traction in modern JavaScript projects.
| Feature | UUID | NanoID |
|---|---|---|
| Output length | 36 characters (with hyphens) — e.g. 550e8400-e29b-41d4-a716-446655440000 | 21 characters by default — e.g. V1StGXR8_Z5jdHi6B-myT |
| Character set | Hexadecimal (0-9, a-f) with hyphens — not URL-safe without encoding. | URL-safe alphabet (A-Za-z0-9_-) — safe in URLs without encoding. |
| Collision resistance | Extremely low — 2^122 possible UUIDs (v4). | Comparable — ~2^126 combinations at default 21 chars. |
| Performance | Fast — native crypto.randomUUID() in modern browsers and Node. | Slightly faster — optimised for JS, smaller bundle footprint. |
| Standardisation | RFC 4122 standard — universally supported across all languages and DBs. | No formal standard — JS-first, ported to other languages. |
| Bundle size | 0 bytes — built into browsers and Node.js natively. | ~130 bytes (minified + gzipped) — tiny but not zero. |
| Human readability | Recognisable format but long and hard to read. | Shorter but less recognisable — no standard visual format. |
UUID Pros & Cons
Pros
- RFC standard — works everywhere, no library needed
- Native support in browsers (crypto.randomUUID), Node.js, PostgreSQL, MySQL
- Universally recognised format — easy to debug and log
- Zero bundle size when using native APIs
- Works out of the box in all databases as a primary key type
Cons
- 36 characters is verbose for URLs, QR codes, or short links
- Not URL-safe — hyphens are fine but hex is less compact
- Larger storage footprint than shorter IDs
NanoID Pros & Cons
Pros
- Shorter (21 chars) — better for URLs, tokens, and display
- URL-safe by default — no encoding needed
- Customisable size and alphabet
- Slightly faster generation in JS benchmarks
Cons
- Requires a dependency — adds to bundle
- No formal standard — less recognised outside JavaScript ecosystem
- Not natively supported in databases as a type
- Less tooling support (no built-in DB functions)
Verdict
Use UUID (v4) when working across multiple languages, databases, or systems — it's the universal standard and has zero dependencies. Use NanoID when URL-friendliness and shorter IDs matter (tokens, short links, client-side IDs) and you're working primarily in JavaScript. For most backend systems and databases, UUID is the safer default.