UUID Generator

Generate standards-compliant UUIDs of version 1, 3, 4 and 5 — one at a time or in batches of up to 100. Random v4, time-based v1, and deterministic name-based v3 and v5, all in your browser.

Free, no sign-up Generated in your browser RFC 4122 compliant

How to Generate a UUID

Three steps, all in your browser.

1

Choose a version

Pick v4 for a simple random ID, v1 for a time-based one, or v3 / v5 when you need the same input to always produce the same UUID. v4 is the right default for most uses.

2

Set the options

Choose how many to generate, up to 100 at once. For v3 and v5, pick a namespace (DNS, URL, OID, X.500 or your own) and type a name to hash into a deterministic identifier.

3

Copy what you need

Copy a single UUID or the whole batch with one click, in lowercase or uppercase. Need a checksum instead of an identifier? Try the Hash Generator.

Frequently Asked Questions

What is a UUID?
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups, like 123e4567-e89b-12d3-a456-426614174000. Its purpose is to give something a unique identity without a central authority: two systems can each generate a UUID and be confident they will not collide. UUIDs are used for database keys, API request IDs, file names and distributed-system identifiers — anywhere you need a unique label that can be created offline, on any machine.
What is the difference between UUID v1, v3, v4 and v5?
They differ in how the bits are filled. Version 4 is random: almost all of its bits come from a random source. Version 1 is time-based: it encodes a timestamp plus a node identifier, so v1 UUIDs are roughly sortable by creation time but reveal when they were made. Versions 3 and 5 are name-based: they hash a namespace plus a name into a UUID, so the same namespace and name always produce the same UUID. The only difference between v3 and v5 is the hash function: v3 uses MD5 and v5 uses SHA-1, with v5 generally preferred.
Which UUID version should I use?
For most needs — database keys, request IDs, random tokens — version 4 is the right default: it is simple, has no metadata to leak, and the chance of collision is negligible. Choose version 1 if you specifically want identifiers that embed a timestamp and can be ordered by creation time. Choose version 5 (or version 3 for legacy compatibility) when you need the same input to always map to the same UUID — for example deriving a stable ID from a URL or a name. When in doubt, use v4.
How do name-based UUIDs (v3 and v5) work?
A name-based UUID is the hash of two things: a namespace (itself a UUID, identifying the kind of name) and a name string within that namespace. The tool hashes the namespace's bytes followed by the name — using MD5 for v3 or SHA-1 for v5 — then sets the version and variant bits to make a valid UUID. Because hashing is deterministic, the same namespace and name always yield the same UUID on any machine. Standard namespaces exist for DNS names, URLs, OIDs and X.500 names, and you can also paste your own namespace UUID.
Are v4 UUIDs random enough to be unique?
Yes, for all practical purposes. A version 4 UUID has 122 random bits, generated here with the browser's cryptographically secure random number generator (crypto.getRandomValues). The number of possible values is so large that you could generate billions of UUIDs per second for a lifetime and never expect a collision. This is why v4 is trusted for primary keys in large systems without any coordination between generators. Because the randomness is cryptographic, the values are also unpredictable, not just unlikely to repeat.
Is anything generated on a server or stored?
No. Every UUID is generated locally in your browser — random v4 values from the Web Crypto API, and name-based v3 and v5 values hashed on your device — so nothing is sent to or created on a server. Nothing you generate or type (including names for v3 and v5) is logged or stored, there is no account, and there is no sign-up. Copy a single UUID or the whole batch with one click. Reloading or closing the tab discards everything, and because there are no network calls the generator works offline once loaded.