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Tools/UUID

UUID Generator

Generate cryptographically secure UUID v4 identifiers using crypto.randomUUID(). Generate up to 50 at once — copy individually or all together.

All processing happens in your browser — nothing is sent to our servers
0c4d5190-8c97-4f74-85e8-08eff5029b45
2793cd03-03d4-4224-8c9b-d339ff2d8ca5
480aeb38-84d6-435e-b4f6-d9d1316dc0c6
bae4ec44-d598-42d4-a99c-9216b069373e
ec001103-0911-4529-b9b7-4c187d35b859

UUID v4 — What You Need to Know

UUID v4 uses 122 bits of randomness, giving ~5.3 × 10³⁶ possible values. The probability of a collision when generating 1 billion UUIDs is roughly 1 in 10²³ — effectively zero for any practical use. Safe to use as database primary keys, idempotency keys, session IDs, and trace IDs.crypto.randomUUID() is available in all modern browsers and Node.js 15+.

How it works
UUID v4 Generation
01Random bits

122 bits of cryptographically random data from crypto.randomUUID() (internally uses crypto.getRandomValues)

02Version nibble

Bits 48–51 set to 0100 (hex 4) — identifies this as a version 4 UUID

03Variant bits

Bits 64–65 set to 10 binary — marks RFC 4122 / ITU-T X.667 variant

04Hex formatting

128 bits written as 32 hex characters grouped 8-4-4-4-12 with hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Spec: RFC 9562 §5.4 (UUID v4), replaces RFC 4122

UUID v4 is not sequential and not suitable as a database primary key in high-write systems (index fragmentation). Consider UUID v7 (time-ordered) for database IDs.

Frequently Asked Questions