UUID Generator
Generate random UUID v4 identifiers. Use singly or in bulk. All generation happens locally.
About this tool
The UUID Generator creates random UUID v4 (Universally Unique Identifier version 4) values instantly in your browser. UUIDs are 128-bit identifiers used across software development — as database primary keys, API request IDs, session tokens, and distributed system identifiers. They eliminate the need for centralized ID coordination.
This tool uses the browser's crypto.getRandomValues() API to generate cryptographically random UUIDs that conform to the RFC 4122 v4 specification. Each UUID has 122 bits of entropy, making collisions practically impossible — you would need to generate about 2.7 × 1018 UUIDs to have a 50% chance of a single collision.
Choose from three output formats: standard dash-separated, compact no-dash, or uppercase. All UUIDs are generated locally — nothing leaves your browser.
How to use
- Choose a format. Select "Standard" for dash-separated UUIDs (recommended), "No dashes" for compact IDs, or "Uppercase" for all-caps output.
- Select quantity. Choose how many UUIDs to generate — from 1 to 50 at a time. For database seeding or testing, 10-25 is a common batch size.
- Generate and copy. Click "Generate" to create UUIDs, then "Copy All" to copy them to your clipboard. Each UUID is on its own line for easy pasting into code or spreadsheets.
Frequently asked questions
What is a UUID and what does v4 mean?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. Version 4 (v4) UUIDs are generated from random numbers, making them practically collision-free. They are widely used as database primary keys, API identifiers, and distributed system IDs.
Are these UUIDs truly unique?
UUID v4 uses 122 bits of random data, giving 2122 possible values (~5.3 × 1036). The chance of collision, even when generating billions of UUIDs, is negligible. The generator uses the browser's cryptographically secure random number generator (crypto.getRandomValues()), not the predictable Math.random().
How many UUIDs should I generate at once?
For database seeding or testing, 25-50 is common. For one-off IDs, generate 1 at a time. For bulk operations, 50 is usually sufficient. All UUIDs are generated instantly in your browser.
Does this work on mobile?
Yes. The UUID Generator is fully responsive and works on all modern browsers including iOS Safari and Android Chrome.