UUID / ULID Generator
Pick UUID v4, UUID v7 or ULID, choose how many (1 to 100) and press Generate. Identifiers come from your browser's secure random number generator, are never sent anywhere, and can be copied one by one, all at once, or downloaded as a .txt file.
Runs in your browser
Free, no sign-up. Identifiers are generated in your browser with crypto.getRandomValues. Nothing is sent to a server or kept in storage.
UUID / ULID Generator
Generate secure UUID v4 values or sortable ULIDs in your browser.
Current Mode
UUID v4
UUID v4 is random and widely supported for database keys, sessions, and API identifiers.
How to use the UUID / ULID Generator
- Choose the type: UUID v4 (random), UUID v7 (time-ordered) or ULID (time-ordered, shorter).
- Set the number of identifiers between 1 and 100. Values outside that range are clamped.
- Press Generate. Changing the type also generates a new list; changing only the count does not until you press Generate.
- Copy a single identifier with its Copy button, use Copy all for the whole list, or press Download .txt to save one identifier per line.
Worked example
Sample data
Types: UUID v4, UUID v7, ULID. Count: 1 each (ULID: 2).
UUID v4: 1ed6a085-afb7-40da-9e1f-4a414afdab7f UUID v7: 01a130ad-13ef-7f17-bc6a-3f799e8a6772 ULID: 01M4RAT4ZFGT77GAJJ5GZ55NV2 ULID: 01M4RAT4ZFGT77GAJJ5GZ55NV3
These are real outputs in each format, so your values will differ. The two ULIDs were made in the same millisecond, so the second is the first with its last character incremented, which keeps them in order. The v4 value has 4 as the first digit of the third group and 9 as the first digit of the fourth; the v7 value has 7 there.
How it works
UUID v4: random
A UUID is 128 bits shown as 32 hex digits in groups of 8-4-4-4-12. Version 4 fills almost all bits from crypto.getRandomValues, then sets the version bits to 0100 (the leading 4 of the third group) and the variant bits to 10 (so the fourth group starts with 8, 9, a or b).
That leaves 122 random bits. Collisions are possible in theory but so unlikely that you can treat them as unique in practice; uniqueness is probabilistic, not guaranteed.
random bits = 128 - 4 (version) - 2 (variant) = 122
UUID v7: sortable by time
Version 7 begins with a 48-bit Unix timestamp in milliseconds, followed by the version digit 7, the variant bits and random bits. Because the time comes first, v7 values sort roughly in creation order, which is friendlier to database indexes than fully random v4 values.
The timestamp is visible in the identifier, so v7 reveals approximately when it was created.
ULID: sortable and compact
A ULID is 26 characters of Crockford base32: 10 characters for a millisecond timestamp and 16 characters of randomness. The alphabet leaves out I, L, O and U to avoid look-alikes.
Within the same millisecond this tool increments the previous random part by one, so ULIDs created together stay in strictly increasing order.
Choosing a type
Use v4 when you want opaque identifiers that reveal nothing. Use v7 or ULID when you want identifiers that index well and sort by creation time.
None of these are secrets or access tokens. Anyone who sees an identifier can use it, so do not rely on it for authorization.
Inputs, outputs and limits
Inputs
- Identifier type: UUID v4, UUID v7 or ULID
- Count from 1 to 100
Outputs
- A list of identifiers, one per line
- Copy for a single identifier or the whole list
- A .txt download
Limits
- Up to 100 identifiers per run; larger counts are clamped to 100
- Uniqueness is probabilistic, not checked against any database
- Identifiers are not stored, so the list is lost when you leave the page
Processing
- Identifiers are generated in your browser with crypto.getRandomValues. Nothing is sent to a server or kept in storage.
Frequently asked questions
Are the identifiers generated on a server?
No. They are created in your browser with its secure random number generator, and the tool never sends the values anywhere or keeps them after you leave the page.
Can two generated UUIDs be the same?
In theory yes, but a v4 UUID has 122 random bits, so a collision is astronomically unlikely. The tool does not check against your existing data, so keep a unique constraint in your database.
What is the difference between UUID v4 and v7?
v4 is entirely random. v7 starts with a millisecond timestamp so values sort by creation time, which helps database indexing, but it reveals roughly when the ID was made.
What is a ULID and how is it different from a UUID?
A ULID is a 26-character, time-sortable identifier in Crockford base32 with a 48-bit timestamp and 80 random bits. It has the same size as a UUID but a shorter text form.
Why are the last characters of consecutive ULIDs almost the same?
ULIDs made in the same millisecond share the timestamp, and the tool adds one to the previous random part so the order is guaranteed. The values are still valid and unique.
Is it safe to use these as passwords or API keys?
No. They are meant as identifiers, not secrets. Use a password manager or a purpose-built secret generator for credentials.
Common uses
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