UUID Generator
Version-4 UUIDs from your browser's cryptographic random source — singly or in bulk, with formatting options. Nothing leaves your device.
How to use this tool
- Click Generate for a fresh UUID — or set a count for a bulk list.
- Toggle uppercase or hyphen-free formatting if your system needs it.
- Copy one or the whole list.
How it works
These are version-4 UUIDs: 122 random bits from the browser's cryptographically secure generator (crypto.randomUUID / getRandomValues), with 6 bits fixed to mark the version and variant. The random space is so large (2¹²²) that collisions are a practical impossibility — you could generate a billion per second for decades without expecting one.
Frequently asked questions
Should I use v4 or v7?
v4 is pure randomness — maximum anonymity, fine everywhere. v7 (RFC 9562, 2024) starts with a millisecond timestamp so IDs sort by creation time, which makes database inserts faster and keys roughly chronological. Prefer v7 for new database primary keys; prefer v4 when the ID must not reveal its creation time.
What's the difference between UUID v4 and v7?
v4 is pure randomness; v7 (newer) embeds a timestamp prefix so IDs sort by creation time, which databases like for index locality. This tool generates v4 — the universal default.
Are these truly unique?
Not guaranteed by math, but effectively yes: with 2¹²² possibilities, the chance of ever seeing a collision in your system is negligible.
Can I use these as secrets or tokens?
Prefer purpose-made secrets for authentication. A v4 UUID has 122 random bits — strong — but standard formats can leak into logs and URLs; treat session tokens with dedicated generators and storage discipline.