What is UUID v7 and should I use it instead?

UUID v7 (RFC 9562) embeds a Unix timestamp in the most significant bits, making UUIDs time-sortable. This improves database index performance for time-ordered inserts. For new projects with time-ordered data, UUID v7 is worth considering over v4.

How likely is a UUID collision?

Astronomically unlikely. To have a 50% chance of a single collision, you would need to generate ~2.71 quintillion UUIDs. At 1 billion per second, that would take 85 years. NanoID's collision probability is similar.

Can I use NanoID for database primary keys?

Yes, store it as VARCHAR(21). The trade-off is no native database type — UUID has dedicated column types in PostgreSQL and MySQL that store it as 16 bytes, more efficient than VARCHAR.

How do I generate a UUID in JavaScript?

Use the built-in: const id = crypto.randomUUID(). No npm package needed — works in all modern browsers and Node.js 14.17+. For NanoID: npm install nanoid, then import { nanoid } from "nanoid"; const id = nanoid();

Last updated: April 11, 2026

UUID vs NanoID — Which Unique ID Generator Should You Use?

Quick Answer

UUID v4 is the universal standard — use it for database primary keys, distributed systems, and anywhere interoperability matters. NanoID is better when you need a shorter, URL-safe ID (21 chars vs 36 chars) for URLs or user-facing strings. Both have negligible collision probability for any practical scale.

UUID v4 vs NanoID — Side by Side

Feature	UUID v4	NanoID
Length	36 characters (32 hex + 4 dashes)	21 characters (default, configurable)
Character set	Hexadecimal (0-9, a-f)	URL-safe (A-Za-z0-9_-)
URL safe	No — hyphens ok in paths, not query params	Yes — all characters URL-safe by default
Entropy	122 bits	~126 bits (21 chars × 6 bits)
Sortable	No (v4 is random)	No (random by default)
Standard	RFC 4122 — universally supported	Not a formal standard
Native support	crypto.randomUUID() — built into browsers and Node.js	npm package required
Database type	Native UUID type in PostgreSQL, MySQL	Store as VARCHAR
Bundle size	Zero — native API	~130 bytes (minified+gzipped)

Verdict

Use UUID v4 as your default — it is a universal standard with native browser and Node.js support (crypto.randomUUID()), database-native types in PostgreSQL and MySQL, and zero dependencies. Use NanoID when you need shorter IDs in URLs or user-facing strings. If you need sortable time-ordered IDs, consider UUID v7 or ULID instead.

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