UUID Generator

A UUID (Universally Unique Identifier, also called a GUID) is a 128-bit value, almost always written as 32 hexadecimal characters split into five groups (8-4-4-4-12, e.g. 3f2504e0-4f89-11d3-9a0c-0305e82c3301), used as a globally unique identifier without needing a central authority to hand them out. They're everywhere: database primary keys, API resource IDs, session tokens, file names for uploaded assets — anywhere you need an identifier that won't collide with one generated somewhere else, ever.

This tool generates one or many UUIDs at once, entirely with your browser's cryptographically secure random number generator. Two versions are supported: version 4, the overwhelmingly common variant, which is 122 bits of pure randomness (the other 6 bits are fixed to mark the version and variant); and version 7, a newer format (standardized in RFC 9562) that encodes a 48-bit millisecond timestamp in its first bits, so — like a ULID — a list of v7 UUIDs sorts in creation order instead of scattering randomly, while still fitting the exact same 128-bit, 5-group shape every UUID library already expects.

Output can be customized to match whatever a specific system expects: lowercase (the RFC-standard convention) or UPPERCASE, and with or without the hyphens that visually separate a UUID's five groups. Already have a UUID and want to know what it is? Paste it into the decoder to see its version and variant, and — for a v7 UUID — its embedded creation timestamp, decoded to a readable date.

Everything — generation and decoding — runs as plain JavaScript directly in your browser, using the same Web Crypto API that powers encryption keys. No identifier you generate or decode is ever uploaded, logged, or transmitted anywhere.