UUID Generator — Guide

Generate UUIDs online for free — v4 random, v1 time-based, v3/v5 namespace UUIDs and NIL, with one-click copy.

What it is and when to use it

A UUID (Universally Unique Identifier) is a 128-bit label, and version 4 — the default here — is generated from random data. With about 122 random bits, the chance of two v4 UUIDs colliding is negligible, so machines can generate identifiers independently without any central coordinator. This tool can also produce v1, v3 and v5 when you need time- or name-based identifiers.

Generates UUIDs in bulk (v4 by default) for test data or unique identifiers.

How to use it

  1. Choose how many you need
  2. Click generate
  3. Copy and use them

Things that trip people up

  • UUID v4 is random and not time-sortable; use ULID if you need an ordered identifier

Questions people ask

Can two generated UUIDs ever collide?
Theoretically yes, practically no — you would need to generate billions per second for a long time to reach even a coin-flip chance. Databases keep unique constraints as a backstop, not because you will hit it.
UUID v4 or ULID — which one do I need?
v4 is completely random, so sorting by UUID says nothing about creation order. If identifiers land in database indexes where insertion order matters, a time-ordered format such as ULID or UUID v7 performs better.
Are the generated UUIDs sent anywhere?
No. They are generated locally in your browser and never leave the page.

Next steps

Open the UUID Generator tool

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