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UUID / GUID Generator

Generate unique UUID and GUID identifiers. Choose the version, count, format, and copy them instantly.

How the UUID Generator Works

A UUID (Universally Unique Identifier) is a 128-bit identifier defined by RFC 9562. Version 4 (v4) uses random data. Version 7 (v7) combines a Unix timestamp in milliseconds with random bits, making it better suited for time-ordered identifiers. The entire process runs in your browser.

Where It Helps

  • Primary keys in databases
  • API request and transaction identifiers
  • Unique file and resource names
  • Correlation IDs for logs and diagnostics
  • Software testing and development

Which UUID version to choose

For most cases, UUID v4 is enough. If you store identifiers in a database or frequently sort them by creation time, UUID v7 can be the more practical choice.

What a UUID contains

Point at an item in the list to highlight it.

Breakdown of a version 4 and a version 7 UUID Version 4 and version 7 UUIDs split into 8-4-4-4-12 groups with the version, variant, random bits and the version 7 timestamp marked. UUID v4 f 4 7 a c 1 0 b - 5 8 c c - 4 3 7 2 - a 5 6 7 - 0 e 0 2 b 2 c 3 d 4 7 9 UUID v7 0 1 9 2 0 c 3 e - 7 b 4 a - 7 c 1 d - 9 f 2 e - 5 b 6 a 8 c 0 d 1 e 2 f 8 4 4 4 12 time in milliseconds
  1. 8-4-4-4-12 groups. 32 hexadecimal characters (128 bits) separated by hyphens. With the hyphens, a UUID is 36 characters long.
  2. Version. The first character of the third group says how the UUID was made: 4 means random, 7 means time-based.
  3. Variant. The variant is the first two bits of the fourth group (binary 10). That is why its first character is always 8, 9, a or b. The other two bits of that character are random in version 4.
  4. Random bits. Version 4 has 122 random bits, which is why two generated UUIDs practically never collide.
  5. Timestamp. Version 7 starts with the time in milliseconds (48 bits), so newer UUIDs sort by creation time.
Version Best for Note
UUID v4 Public IDs, file names, test data, and general random identifiers The most familiar and widely supported option.
UUID v7 Database rows, logs, events, and correlation IDs Sorts more naturally by creation time.

Format, hyphens, and letter case

The common UUID form has 36 characters including hyphens. Without hyphens, it has 32 hexadecimal characters. Lowercase and uppercase represent the same value; the choice mostly depends on the system where you paste the UUID.

With hyphens
018f6f5a-6c2b-7a1e-9f2d-0b4c8e7a9123
Without hyphens
018f6f5a6c2b7a1e9f2d0b4c8e7a9123

A UUID is not a secret token

A UUID is an identifier, not a security mechanism. It may be hard to guess, but it should not replace passwords, access tokens, or authorization checks.

  • Use it as an ID for a record, file, event, or request.
  • Do not rely on it as the only protection for access.
  • If the UUID appears in a URL, treat it as a public identifier.

FAQ

What is the difference between UUID v4 and UUID v7?

UUID v4 is random and is the most commonly used version. UUID v7 includes a time component based on Unix milliseconds, so it sorts more naturally by creation time. For general use, v4 is enough; for databases and logs, v7 can be more practical.

Are generated UUIDs truly unique?

Yes. The probability of a UUID v4 collision is extremely low (1 in 2122). UUID v7 combines a time component with random bits, so it is also practically unique in normal use.

What is the difference between UUID and GUID?

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. The term GUID is more common in Microsoft environments, while UUID is the standard term in RFC 9562, which replaced the older RFC 4122.