RFC 4122 Compliant

Free UUID v4 Generator Online — Crypto-Random

Generate cryptographically secure version 4 UUIDs using the Web Crypto API. Bulk generation up to 1000, multiple formats, and instant copy. Compliant with RFC 4122.

122-bit randomness Browser-native crypto 100% private
Your Generated UUID
Quantity (1–1000)
Format

Crypto-Secure

Uses crypto.getRandomValues() for true randomness.

Bulk Generation

Generate up to 1,000 UUIDs at once with one click.

5 Output Formats

Hyphenated, plain hex, braces, URN, or Base64 encoded.

Customizable

Toggle uppercase, quotes, and comma separators on the fly.

What is a UUID v4?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit identifier standardized by RFC 4122. Version 4 UUIDs are generated entirely from random or pseudo-random numbers, with the version and variant bits fixed by the spec.

The probability of generating a duplicate is so astronomically small that, for practical purposes, every UUID v4 you generate is unique forever. This makes them ideal for primary keys, distributed systems, file names, session tokens, and API request IDs.

Anatomy of a UUID v4

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
time_low (8 hex) — Random 32 bits.
time_mid (4 hex) — Random 16 bits.
version (4 hex) — Always starts with 4, identifying this as a v4 UUID.
variant (4 hex) — First hex char is 8, 9, a, or b (RFC 4122 variant).
node (12 hex) — Random 48 bits.

Common Use Cases

Database primary keys (especially in distributed databases), API resource IDs, session tokens, idempotency keys, file naming to avoid collisions, message identifiers in queues like Kafka and RabbitMQ, and tracking IDs in microservice request chains.

Is this generator secure?

Yes. This tool uses crypto.getRandomValues() — the same cryptographically secure random source browsers use for TLS and WebCrypto operations. No UUID is ever sent to a server; every byte is generated locally on your device.

Copied!