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OfflineBench

UUID generator (GUID)

Generate UUID v4, sortable UUID v7 and ULIDs, up to 1,000 at a time, or inspect a UUID’s version and timestamp.

0 bytes uploadedProcessed on this device How it works

Generate

Inspect

With or without hyphens, in braces, or as urn:uuid:…

Paste a UUID

See its version and variant, and when it was created for versions 1, 6 and 7.

How to generate UUIDs

  1. Choose a Type: UUID v4 (random), the default, UUID v7 (time-ordered) or ULID. A new value appears straight away.
  2. Set How many, from 1 to 1,000. For UUIDs, turn on Uppercase or turn off Hyphens if your system needs that form; ULIDs are always uppercase without hyphens.
  3. Copy a single value with its copy button. For a batch, select Copy all or download them as a .txt file, one per line. Generate new makes a fresh set.
  4. To check a UUID, paste it under Inspect to see its version, variant and, for versions 1, 6 and 7, when it was created. Hyphens, braces and the urn:uuid: prefix are accepted.

UUID v4, v7 and ULID

UUID v4
122 random bits, for example 919108f7-52d1-4320-9bac-f847db4148a8. The 4 at the start of the third group is the version.
UUID v7
A 48-bit millisecond timestamp, then random bits (RFC 9562). Values created later sort later, which keeps database indexes compact. Within one millisecond a counter keeps a batch in order.
ULID
26 characters of Crockford Base32, for example 01ARYZ6S41TSV4RRFFQ69G5FAV: 10 for the time, 16 random. Sortable, shorter than a UUID, and without ambiguous letters (no I, L, O or U).

How the values are made

The random bits come from your browser’s cryptographic random number generator (crypto.getRandomValues). UUID v7 and ULID also take the time from your device’s clock, so their timestamps are only as accurate as that clock.

Troubleshooting

  • “This has 31 hex digits.” A UUID has exactly 32 hex digits, so part of it was probably lost when copying. Copy it again in full.
  • Version shows “Not an RFC 9562 UUID.” The variant bits (the first digit of the fourth group) aren’t 8, 9, a or b. Some older Microsoft GUIDs use another variant; the value can still be a valid identifier.
  • “This looks like a ULID.” The inspector reads UUIDs only. A ULID’s first 10 characters are its creation time in milliseconds.
  • No creation time is shown. Only versions 1, 6 and 7 contain a timestamp. Version 4 is entirely random.

How your data stays private

Everything happens in your browser, on your device. Your files and text are never uploaded, never stored, and never put in the address bar.

  • The site’s security policy (connect-src 'self') tells your browser to block any attempt by the page to send data to another server.
  • Only your preferences, such as the theme and a tool’s last-used options, are saved in your browser’s local storage. Never your content.
  • To check it yourself, open your browser’s developer tools, select the Network tab, and use the tool: no request carries your data.

There is no account, no sign-up and no watermark. After your first visit, pages open without a connection; a tool’s larger parts, such as the PDF and image engines, are saved the first time you use it, so it works offline from then on.

Frequently asked questions

What is the difference between UUID v4 and v7?

UUID v4 is 122 random bits: unpredictable, with no order. UUID v7 starts with the time in milliseconds, followed by random bits, so values sort in the order they were created. That makes v7 a better database key: new rows go to the end of the index instead of random places. Use v4 when the id must not reveal when it was made.

Is a GUID the same as a UUID?

Yes. GUID (globally unique identifier) is Microsoft’s name for a UUID. The format is the same 128-bit, 32-hex-digit value, often written in braces in Windows tools, for example {919108f7-52d1-4320-9bac-f847db4148a8}. Turn on Uppercase if your system expects GUIDs in capitals. The inspector accepts GUIDs with or without braces.

Are the generated UUIDs random and unique?

They come from your browser’s cryptographic random number generator (crypto.getRandomValues), the same source used for encryption keys. With 122 random bits, the chance of two v4 UUIDs colliding is negligible even across billions of values. Nothing is generated on or sent to a server.

Can I generate UUIDs in bulk or without hyphens?

Yes. Set the quantity up to 1,000 and copy them all or download them as a .txt file, one per line. Turn on Uppercase for capital letters, or turn off Hyphens for the 32-digit form.

What is a ULID?

A ULID is a 128-bit id like a UUID, written as 26 characters in Crockford’s Base32 (for example 01ARYZ6S41TSV4RRFFQ69G5FAV). It starts with a millisecond timestamp, so ULIDs sort by creation time, like UUID v7. Choose UUID v7 when your database has a UUID type, and ULID when you want shorter text ids.

How do I find out when a UUID was created?

Paste it under Inspect. For versions 1, 6 and 7, which contain a timestamp, you see the date and time it was created. Version 4 UUIDs are random and contain no time.

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