UUID Generator

Pick a version above, or accept the v4 (random) default, and a fresh id appears immediately — generated by your browser's own cryptographic random number source, never sent anywhere. Turn on bulk generation to get up to 500 at once, formatted the way whatever you're pasting into expects, and use the validator at the bottom to check a UUID or GUID someone else handed you.

GUID generator: is a GUID the same as a UUID?

Yes — completely. "UUID" and "GUID" name the identical 128-bit value; the difference is only which world you learned the term in. UUID (Universally Unique Identifier) is the name used by the original OSF specification and by most languages, Unix-family tools and RFCs; GUID (Globally Unique Identifier) is Microsoft's name for the same thing, and it's the term you'll see in C#, .NET, SQL Server's UNIQUEIDENTIFIER column type, and the Windows registry. The one place the two worlds visibly differ is formatting convention, not the underlying value: a GUID pasted from SQL Server or the registry often arrives wrapped in curly braces, like {550e8400-e29b-41d4-a716-446655440000} — which is exactly why the "Wrap in braces" option below exists, and why the validator strips a leading and trailing brace before checking a pasted value rather than rejecting it as malformed.

UUID v4 generator: what "random uuid v4" means

Every id this tool generates states its version out loud, because "a UUID" on its own is ambiguous — the specification defines eight different schemes for building one, and they are not interchangeable. Version 4 is the one most people mean when they say "a UUID" with no qualifier: 122 bits are genuine random output from a cryptographic random number generator, and the remaining 6 bits are fixed to mark the id as version 4 under the RFC 4122 variant — that fixed nibble is why every v4 UUID this tool produces has a 4 in the same position (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx) and a y that is always 8, 9, a or b. Nothing about a v4 id encodes when it was created, where it came from, or anything else about its origin — it is pure randomness with a version label stapled on, which is exactly the property that makes it safe to use as a security token or a public-facing identifier.

UUID v7 generator: time-ordered ids for database keys

Version 7 keeps the same 128-bit shape but spends its first 48 bits on a Unix millisecond timestamp instead of randomness, so two v7 ids generated further apart in time always sort in the order they were created — the remaining 74 non-fixed bits are still genuinely random, so two ids minted in the very same millisecond are ordered only by chance between themselves. This is worth having for one specific, increasingly common reason: a v4 id is 122 bits of pure randomness with zero relationship to when it was inserted, so as a table grows, every new row lands at a random position scattered across the whole index rather than appending near the end. On the B-tree index most relational databases build by default, that pattern causes constant page splits and poor cache locality — new rows should be cheap to insert, and with a v4 primary key on a large table, they increasingly aren't. A v7 id restores the append-mostly access pattern an auto-incrementing integer gives you, while still letting any client generate one independently with no round trip to a central counter and no realistic collision risk. The one thing you give up: the leading timestamp bits mean anyone who can see a v7 id can read off roughly when the row behind it was created, which a v4 id never reveals. If that leak is unacceptable for what the id identifies — a password-reset token being the clearest case — use v4 instead.

Bulk UUID generator: formats for pasting into code

Turn the count above 1 and every id fills the box below, one per line by default, with the same formatting options applied: uppercase or lowercase, with or without hyphens, and wrapped in { } for a value headed into SQL Server or the Windows registry. Turn on "Quoted list" when you're pasting straight into source code — it wraps each id in double quotes and joins them with a trailing comma and newline, the shape a string[] literal or a JSON array element already needs, so there's no follow-up find-and-replace before it compiles. "Copy all" copies exactly what the box shows, formatting and all.

UUID validator: check a pasted id and its version

Paste any string into the validator to find out two things: whether it is a syntactically valid UUID at all, and if so, which version and variant it claims to be. The check accepts the standard hyphenated form, a bare 32-digit hex string with no hyphens, and a brace-wrapped GUID — so a value copied straight out of a .env file, a JSON payload or SQL Server's UI validates the same way. "Valid" here means the shape is a well-formed 128-bit UUID; it cannot tell you whether the id was actually generated correctly upstream, the same way checking that a string is 16 digits doesn't confirm it's a real credit card number. The nil UUID and the "max" UUID (all fs) both validate as shape-correct with no version, which is expected — neither is a randomly generated id, so neither carries a version number to report.

Nil UUID

00000000-0000-0000-0000-000000000000 is the one UUID that is never generated randomly — it's a reserved value the specification sets aside to mean "no id" or "not set," the UUID equivalent of a null reference or an empty string used as a sentinel rather than a real value. It's included here, alongside its own copy button and the same formatting options as everything else, because the moment you need one you usually need it in the same format as the ids around it — braced for a SQL Server default, or bare for a config file.