What's the difference between UUID v4 and UUID v7?

UUID v4 is 122 bits of pure randomness with no ordering; UUID v7 packs a 48-bit millisecond timestamp into the leading bits, so newly generated v7 IDs sort after older ones, which helps with database index locality.

Is a GUID the same thing as a UUID?

Functionally yes, GUID is Microsoft's name for the same 128-bit format; this tool's GUID option produces an uppercase UUID v4 to match the casing .NET's Guid type typically displays.

How random are the IDs this tool generates?

All four kinds pull their random bytes from crypto.getRandomValues, the browser's cryptographically secure random number generator, not Math.random, so they're suitable as unique identifiers, not just for display mockups.

Why would I use a ULID instead of a UUID?

ULID encodes a timestamp and uses Crockford's Base32, so IDs are shorter to type, case-insensitive to compare, and sort chronologically, which UUID v4 cannot do without adding a separate timestamp field.

ID Generator

Generate GUIDs, UUID v4, time-sortable UUID v7 and ULIDs locally, in bulk.

Local, Runs entirely in your browser, your data never leaves your device.

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Generate UUIDs, ULIDs and GUIDs in bulk

This tool generates unique identifiers: random UUID v4, time-sortable UUID v7, Crockford Base32 ULIDs, or uppercase .NET-style GUIDs. All four draw their randomness from the browser's crypto.getRandomValues CSPRNG, and UUID v7 and ULID additionally encode the current timestamp so IDs sort chronologically. You can generate up to 10,000 at once, with options for case, hyphens and braces, and nothing is generated or logged server-side.

How to use the ID Generator

Choose an ID kind: UUID v4, UUID v7, ULID or GUID.
Set how many to generate, from 1 up to 10,000.
For UUID and GUID kinds, toggle uppercase, hyphens and braces to match your format.
Copy the full list, or copy a single generated value.

UUID v7 and ULID both embed a millisecond timestamp in their leading bits, so sorting a list of them lexicographically also sorts it chronologically, unlike UUID v4 where ordering is random.

GUID output here is just an uppercase UUID v4 formatted the way .NET's Guid.NewGuid() prints it; the underlying bits and randomness source are identical to the UUID v4 option.

Frequently asked questions

What's the difference between UUID v4 and UUID v7?: UUID v4 is 122 bits of pure randomness with no ordering; UUID v7 packs a 48-bit millisecond timestamp into the leading bits, so newly generated v7 IDs sort after older ones, which helps with database index locality.
Is a GUID the same thing as a UUID?: Functionally yes, GUID is Microsoft's name for the same 128-bit format; this tool's GUID option produces an uppercase UUID v4 to match the casing .NET's Guid type typically displays.
How random are the IDs this tool generates?: All four kinds pull their random bytes from crypto.getRandomValues, the browser's cryptographically secure random number generator, not Math.random, so they're suitable as unique identifiers, not just for display mockups.
Why would I use a ULID instead of a UUID?: ULID encodes a timestamp and uses Crockford's Base32, so IDs are shorter to type, case-insensitive to compare, and sort chronologically, which UUID v4 cannot do without adding a separate timestamp field.