UUID Generator
Generate random UUID v4 identifiers. Create single or batch UUIDs with one click. Uses crypto.getRandomValues for security.
About the UUID Generator
This UUID generator runs entirely in your browser. It produces random UUID version 4 identifiers using the Web Crypto API, so the values are cryptographically secure and never leave your device. Choose how many UUIDs you need, pick a format, then click Generate to create them instantly.
What is a UUID?
A UUID (Universally Unique Identifier), also known as a GUID, is a 128-bit value used to uniquely identify information in distributed systems without central coordination. The most common variant is UUID v4, where 122 of the bits are generated randomly. The chance of two randomly generated UUIDs colliding is astronomically small — roughly 1 in 2.71 × 10^18 when generating 103 trillion UUIDs.
UUID v4 specification
A UUID v4 is written as 32 hexadecimal digits grouped into five segments separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters. The 13th digit is always 4 (the version number), and the 17th digit is always 8, 9, a, or b (the variant). All other digits are random.
When to use UUIDs
- Database primary keys — Avoid sequential IDs leaking row counts and let clients generate IDs before insertion.
- Distributed systems — Generate unique identifiers across machines without a central authority.
- API tokens and request IDs — Correlate requests across microservices without revealing order.
- File and asset naming — Avoid filename collisions when users upload to shared storage.
- Session and transaction tracking — Issue unpredictable session identifiers for security.
Format options
- Standard —
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, the canonical form. - Hyphenated — Same as standard, made explicit for tooling that expects hyphens.
- Braces — Wrapped in curly braces, e.g.
{xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx}, common in Microsoft ecosystems. - URN — Prefixed with
urn:uuid:, the IETF URN representation.
Frequently asked questions
Are these UUIDs unique? UUID v4 values are random and the probability of collision is effectively zero for any realistic workload. You can safely treat them as unique.
Are the generated UUIDs sent anywhere? No. Generation happens locally using the browser's crypto.getRandomValues API. Nothing is uploaded.
What is the maximum count? Up to 1000 UUIDs per click. For larger batches, click Generate multiple times.
Are the UUIDs cryptographically secure? Yes. They use the platform's cryptographically secure random number generator rather than Math.random().