UUID Generator
Generate v4 random or v7 time-ordered UUIDs, one or up to a thousand at a time, and check any UUID for its version and creation time. Free, and everything stays in your browser.
Check a UUID
How to generate UUIDs
Pick a version, choose how many you need (up to 1,000) and press Generate. The list appears in the box, ready to copy or download as a text file. Options let you write them in uppercase, drop the hyphens, or wrap each one in braces, which some Windows tools expect.
Which version should you pick?
| Version | How it is made | Good for |
|---|---|---|
| v4 | 122 random bits | Most uses: record IDs, request IDs, tokens that only need to be unique. The default choice. |
| v7 | 48-bit Unix time in milliseconds, then random bits | Database primary keys. New values sort after older ones, which keeps indexes tight and makes records easy to order by creation time. |
| Nil | All zeros | A placeholder meaning no value. |
| Max | All F | A placeholder for the largest possible value, handy as an upper bound. |
How unique is a random UUID?
A v4 UUID has 122 random bits, about 5.3 undecillion possible values. If you generated a billion every second for a century, the chance of any two matching would still be tiny. In practice duplicates do not happen unless the random source is broken. This page uses the browser’s cryptographic random generator, not Math.random.
Why v7 sorts by time
The first 12 hex digits of a v7 UUID are the time in milliseconds since 1 January 1970. Because they come first, a list of v7 UUIDs sorts in creation order as plain text. IDs made in the same millisecond use a counter so they still increase. The check box below reads this time back out of any v7 UUID you paste.
Checking a UUID
Paste a UUID into the check box to confirm it is well formed and see its version and variant. For version 1, 6 and 7 it also shows the creation time. Braces and a urn:uuid: prefix are accepted.
UUID or GUID?
GUID is Microsoft’s name for the same 128-bit identifier. In everyday use the two words mean the same thing, and the format is the same 8-4-4-4-12 hex layout.
Privacy
Everything runs in your browser. The UUIDs are made on your device and are not sent anywhere or stored.
Frequently asked questions
Are these UUIDs safe to use as IDs in a database?
Yes. Version 4 values are random and effectively unique, and version 7 values are unique and sort by time, which many databases handle better as a primary key. They are generated with the browser’s secure random source.
Can two people generate the same UUID?
In theory yes, in practice no. A v4 UUID has 122 random bits, so the chance of a repeat is negligible even across very large systems.
Is a UUID secret?
No. A UUID is an identifier, not a password. v4 values are hard to guess, but do not treat one as a security credential. Use a proper token or key for that.
What is the difference between v4 and v7?
v4 is fully random. v7 starts with the current time, so it sorts by creation and stays friendlier to database indexes, while still containing random bits to keep values unique.
Does removing the hyphens change the UUID?
No. The hyphens are only formatting. The same 32 hex digits identify the same value with or without them.
Are my generated UUIDs stored anywhere?
No. They are created on your device and shown on this page only. Nothing is uploaded or saved.
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