A fresh UUID is ready below. Choose version 4 or 7, generate up to 1,000 at once, then copy or download them.
Runs in your browser. Nothing you enter is sent to a server.
How it works
Both versions follow RFC 9562, the current UUID standard:
Version 4 fills 122 bits with cryptographically secure random data. The remaining 6 bits mark the version (the 4 at the start of the third group) and the variant (the fourth group starts with 8, 9, a or b).
Version 7 puts the current time, in milliseconds since 1970, in the first 48 bits and fills the rest with random data. Two v7 UUIDs created a second apart sort in that order, both as text and as bytes.
Uppercase and “without hyphens” only change how the UUID is written; the value is the same. Most systems accept either form, but lowercase with hyphens is the standard text format.
Anatomy of a UUID
Part
Example (v7)
Meaning
First 12 hex digits
017f22e2-79b0
Timestamp: 22 February 2022, 19:22:22 UTC
Next digit
7
Version
Next 3 digits
cc3
Random
Next digit
9
Variant (8, 9, a or b)
Last 15 digits
8c4-dc0c0c07398f
Random
Generating UUIDs in code
Language
Version 4
JavaScript (browsers, Node.js)
crypto.randomUUID()
Python
uuid.uuid4()
Java
UUID.randomUUID()
C#
Guid.NewGuid()
PostgreSQL
gen_random_uuid()
Frequently asked questions
What is a UUID?+
A universally unique identifier is a 128-bit value written as 32 hexadecimal digits in five groups, such as 919108f7-52d1-4320-9bac-f847db4148a8. It lets different systems create IDs independently without checking with each other. Microsoft calls them GUIDs; they are the same thing.
Should I use version 4 or version 7?+
Version 4 is fully random and the most widely supported. Version 7 starts with a timestamp, so new IDs sort after older ones. That makes v7 a better choice for database primary keys, because inserts stay close together in the index.
Can two UUIDs ever be the same?+
In theory, yes; in practice, no. A version 4 UUID has 122 random bits. You would need to generate about 2.7 quintillion (2.7 × 10¹⁸) of them to reach a 50% chance of a single duplicate.
Are these UUIDs safe to use?+
They are generated in your browser with the Web Crypto API, the same secure random source used for encryption keys, and are never sent anywhere. Do not use a UUID as a password or secret token, though; use the password generator for that.
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