For Developers
Generate unique identifiers for database records, sessions, file names, or any resource that needs a globally unique ID without a central registry.
Generate unique UUIDs
instantly in your browser.
Create RFC 4122 v4 UUIDs in bulk using the Web Crypto API. Choose lowercase or uppercase, generate up to 100 at once. No signup, no ads, 100% private.
- v4RFC 4122
- 128bit random
- 100%browser-side
- Freeforever
UUID Generator
bae52842-522a-440f-852e-8e6727bcb000Why use a UUID Generator?
Cryptographically Random
Uses crypto.getRandomValues() — the same entropy source used by browsers for cryptographic operations. Not Math.random().
Bulk Generation
Generate up to 100 UUIDs at once. Copy individually or copy all to clipboard with one click for seeding databases or test fixtures.
100% Private
UUIDs are generated locally in your browser. Nothing is logged, stored, or transmitted. Works completely offline.
UUID format guide
Structure
8 hex digits
First segment. 32 bits of random data in the time_low field position (v4 ignores time fields).
xxxxxxxx-…4 + 4 hex digits
Middle segments. The third group's first nibble is always 4, indicating UUID version 4.
…-xxxx-4xxx-…12 hex digits
Final segment. The first nibble is 8, 9, a, or b — the RFC 4122 variant bits.
…-xxxxxxxxxxxxCommon uses
Database primary keys
UUID primary keys work across distributed systems without coordination, preventing ID collisions during merges.
id UUID PRIMARY KEY DEFAULT gen_random_uuid()File & asset naming
Rename uploaded files to UUIDs to prevent collisions and avoid exposing sequential IDs to users.
a3f2c1d0-….jpgSession & token IDs
Use UUIDs as opaque session tokens. Their randomness makes them hard to guess or enumerate.
session_id = uuid_v4()Questions people ask
What is a UUID?
UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. The standard form is 32 hexadecimal digits in 5 groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
What is UUID v4?
UUID v4 is randomly generated. 122 of its 128 bits are random, making collisions practically impossible. It is the most widely used UUID version for generating unique IDs without a central registry.
Are generated UUIDs stored anywhere?
No. UUIDs are generated locally using the Web Crypto API and are never sent to any server. They exist only in your browser.
Can two generated UUIDs be the same?
Theoretically yes, but the probability is astronomically small. With 2^122 possible values, you'd need to generate billions of UUIDs per second for millions of years to expect a collision.
What is the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard. They are functionally identical — the terms are used interchangeably.