UUID Generator

How to use this UUID generator

A UUID (Universally Unique Identifier, sometimes called a GUID on Windows) is a 128-bit value written as a 36-character string like f47ac10b-58cc-4372-a567-0e02b2c3d479. The RFC 4122 spec defines several versions; this tool generates version 4, which is random. Drawing from 122 bits of randomness (6 bits are fixed for versioning and variant), the probability of collision is astronomically low — you could generate a billion UUIDs per second for 85 years before hitting a 50% chance of one duplicate.

1. Pick a count. Generate between 1 and 50 UUIDs at once. Typical use: one for a form, ten for seeding a test fixture, fifty for batch inserts.
2. Choose a format. Toggle uppercase if your target system (SQL Server, some legacy databases) expects uppercase hex. Toggle the surrounding braces for Windows-style GUIDs like {f47ac10b-...}.
3. Hyphens vs. compact. Strip hyphens if you need a 32-character compact form — still unique, just less human-readable.
4. Copy. Use the copy-all button to grab every UUID on the clipboard at once.

When to use UUIDs over sequential IDs. UUIDs are the right answer when IDs must be unique across systems, generated offline or client-side, or unguessable by URL enumeration. They are a poor answer for heavily indexed columns because random writes fragment B-tree pages — prefer UUIDv7 or TSID there. This tool emits v4 because it is the spec everyone supports; if you specifically need time-ordered UUIDs, check your database's native function (PostgreSQL's gen_random_uuid() is v4;uuid_generate_v7() is coming in many drivers).