Générateur UUID

À PROPOS DE CET OUTIL

Click once to generate a randomly generated UUID (version 4), or generate multiple at a time in bulk. A v4 UUID is 128 bits, with 122 bits coming from a random or pseudo-random source and the rest fixed to mark the version and variant per RFC 4122, giving a chance of collision so low it's treated as effectively zero even across billions of IDs. UUIDs are used as unique identifiers for database records, sessions, files, and anywhere a collision-free ID is needed without coordinating with a central counter. Generation happens locally using the browser's cryptographic random number generator, so no ID is ever sent anywhere before you use it.

COMMENT UTILISER

1. Click "Generate" to produce a single UUID v4.
2. Set the quantity if you need a batch, then generate multiple at once.
3. Choose formatting options like uppercase/lowercase or with/without hyphens, if offered.
4. Copy a single UUID or copy the whole list at once.
5. Paste the UUID(s) into your database seed script, code, or config file.
6. Regenerate anytime — every click produces fresh, independent values.

CAS D'USAGE COURANTS

• A backend developer seeds a test database with hundreds of fake primary keys before running integration tests.
• A frontend developer needs a unique "key" prop for a list of dynamically rendered React components.
• A DevOps engineer generates a unique idempotency key to include in an API request header.
• Someone designing a distributed system needs IDs that multiple services can generate independently without a shared counter.
• A QA engineer creates mock user IDs for a batch of test accounts.

CONSEILS ET ERREURS COURANTES

• UUID v4 is random, not sequential — don't rely on generated UUIDs to sort by creation time; use v7-style timestamp-based UUIDs or a separate timestamp column if ordering matters.
• Standard UUID format is 36 characters including 4 hyphens (8-4-4-4-12 hex digits); some systems expect no hyphens, so check formatting before pasting into a strict field.
• A v4 UUID isn't cryptographically meant to be a secret — while collisions are astronomically unlikely, don't rely on a raw UUID as your only defense for something like a password reset token.
• If you need reproducible IDs for testing, generate them once and hardcode them in fixtures rather than regenerating on every test run.

AUTRES QUESTIONS

How likely is a UUID v4 collision?

With 122 random bits, you'd need to generate roughly 2.71 quintillion UUIDs before there's a 50% chance of a single collision, so for virtually all practical applications it's treated as impossible.

Is a UUID the same as a GUID?

Functionally yes — GUID is Microsoft's name for the same 128-bit identifier concept, and UUID is the more general RFC 4122 term used elsewhere.

Why does the UUID always have specific version digits?

In a v4 UUID, the 13th hex digit is always "4" to mark the version, and the first digit of the 4th group is always 8, 9, a, or b to mark the variant, per the RFC 4122 spec.

Can I use a UUID as a database primary key?

Yes, though UUIDs are larger than integers (16 bytes vs 4-8) and their randomness can hurt index locality in some databases, which is why sequential variants like UUIDv7 are gaining popularity for that use case.

GUIDES ASSOCIÉS

OUTILS ASSOCIÉS