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UUID Generator

Create universally unique identifiers for databases, APIs and test data. Generate one or thousands, in the format your code expects, and check whether an existing value is a valid UUID.

  • Runs in your browser
  • No sign-up
  • Free to use
Version

Validate a UUID

How to use UUID Generator

  1. Choose the version: v4 for fully random IDs, or v7 for IDs that sort by creation time.
  2. Set how many you need and the formatting: case, hyphens and braces.
  3. Select Generate.
  4. Copy the list or download it as a text file. Paste a UUID into the validator to inspect it.

UUID Generator features

Version 4 and version 7

Random identifiers, or time-ordered ones that index efficiently in databases.

Bulk generation

Up to 10,000 UUIDs at once.

Formatting options

Upper or lower case, without hyphens, or wrapped in braces as GUIDs often are.

UUID validator

Paste any UUID to check it is valid and see its version, variant and, for v7, its timestamp.

Secure randomness

Random bits come from the browser's cryptographic generator.

When to use UUID Generator

  • Creating primary keys or record IDs for a database.
  • Generating correlation and request IDs for logs and APIs.
  • Filling test fixtures and seed data with unique identifiers.
  • Checking whether a value from a system is a well-formed UUID.

UUID Generator FAQ

What is the difference between UUID v4 and v7?

A v4 UUID is 122 bits of randomness. A v7 UUID starts with a 48-bit millisecond timestamp followed by random bits, so values created later sort after earlier ones. That ordering keeps database indexes compact and fast.

Can two UUIDs be the same?

In theory, yes; in practice, no. With 122 random bits you would need to generate around a billion UUIDs per second for about 85 years before reaching a 50% chance of a single collision.

Is a GUID the same as a UUID?

Yes. GUID is Microsoft's name for the same 128-bit identifier format. GUIDs are often written in upper case and wrapped in braces, which the formatting options reproduce.

Should I use UUIDs as secrets?

No. Although v4 UUIDs are random, they are identifiers, not secrets, and v7 values reveal their creation time. Use a dedicated token generator for passwords and API keys.

Which version does my database need?

Any column of UUID type accepts all versions. Prefer v7 for primary keys in new systems to avoid the random-insert overhead of v4.

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Inside a UUID

A UUID is a 128-bit number written as 32 hexadecimal digits in five groups, 8-4-4-4-12. A few of those bits are fixed: the first digit of the third group states the version, and the first digit of the fourth group encodes the variant, which for standard UUIDs is 8, 9, a or b. The rest carries the identifier itself.

Version 4 fills the remaining bits at random, which makes values unpredictable but scatters them across an index. Version 7, standardised in RFC 9562 in 2024, puts a Unix timestamp in milliseconds at the front. New rows then land at the end of an index rather than at random positions, which reduces page splits and improves insert performance in large tables.

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