What a UUID is
A UUID (universally unique identifier) is a 128-bit value written as 32 hexadecimal digits in five groups, for example 3f2b8c1e-9a47-4d6b-8e21-5c0a7f9d1b34. Version 4 UUIDs are random, so you can create them on any machine without a central counter and still expect them to be unique.
This generator creates version 4 UUIDs using your browser's secure random number generator. Nothing is sent to a server.
How to use it
Choose how many UUIDs you need (up to 50), pick the format options, and generate. Options include uppercase output and removing the hyphens. Copy a single value or the whole list.
Where developers use UUIDs
- Database primary keys when records are created on several services or offline.
- Idempotency keys so a retried API request is not processed twice.
- Correlation IDs to trace one request through logs across services.
- Temporary file names and upload IDs that must not collide.
Format, collisions and common mistakes
The "4" at the start of the third group marks the version, and the first character of the fourth group is 8, 9, a or b. If your validator rejects a UUID, check those positions and the 8-4-4-4-12 grouping.
The chance of two random v4 UUIDs colliding is negligible for normal applications, but a UUID is an identifier, not a secret. Do not use one as a password or access token. For that, use a dedicated password or token generator.
If you store UUIDs as primary keys, note that random values are not ordered, which can affect index locality in some databases.
Related tools
- Secure Password Generator: Generate strong, random passwords with customizable length and character sets.
- Bulk SHA & MD5 Hash Generator: Generate MD5, SHA-1, SHA-256, and SHA-512 hashes in bulk from text or files.
- JSON Formatter & Validator: Format, validate, and beautify JSON with clear error messages for developers.
- Base64 Encoder & Decoder: Encode and decode Base64 strings for APIs, data transfer, and debugging.