UUID Generator
Generate cryptographically-random RFC 4122 v4 UUIDs in your browser.
How to use the UUID Generator
Generate cryptographically random RFC 4122 version 4 UUIDs entirely in your browser. The Web Crypto API supplies the entropy, so the values are safe to use as database keys, request IDs or anywhere you need a globally unique identifier.
- 01Choose how many UUIDs you need with the count selector (1 to 100).
- 02Toggle the format options: uppercase, wrap in braces, or drop the hyphens.
- 03Click generate to roll a fresh batch, then copy a single value or the whole list.
tips
- —At v4, two randomly generated UUIDs collide with probability around 1 in 2.71 × 10¹⁸ — safe to use as primary keys without checking for duplicates.
- —UUID and GUID are the same 128-bit format under different names; Microsoft calls it GUID, everyone else calls it UUID.
- —Dropping hyphens and lowercasing is common for compact storage — just keep the format consistent across your system.
frequently asked
What is a UUID?+
A UUID (Universally Unique Identifier) is a 128-bit identifier defined by RFC 4122, displayed as 32 hex digits in five groups separated by hyphens, e.g. 550e8400-e29b-41d4-a716-446655440000. The v4 variant uses random numbers, making collisions astronomically unlikely.
Are these UUIDs unique?+
Yes. v4 UUIDs use the Web Crypto API (cryptographically secure randomness). The probability of a collision is roughly 1 in 2.71 × 10¹⁸ — you would need to generate over 100 trillion UUIDs for even a 50% chance of a single duplicate.
UUID vs GUID — what is the difference?+
There is no practical difference. GUID (Globally Unique Identifier) is Microsoft’s term for a UUID. They use the same 128-bit format and the same v4 algorithm. Code that accepts one accepts the other.
Is this tool free?+
Yes. No signup required, and generation happens entirely on your device using the browser’s native crypto API.