UUID Generator (v4, v7, v1)
Generate RFC 9562 UUIDs in bulk: random v4, time-ordered v7, timestamp v1, Nil and Max. Uppercase, braces or no hyphens. Uses crypto.getRandomValues.
Up to 1000
122 random bits from crypto.getRandomValues. The chance of a collision is negligible.
What is UUID Generator?
A UUID (universally unique identifier) is a 128-bit ID written as 32 hex digits in the form 8-4-4-4-12. This tool generates up to 1,000 UUIDs at once in version 4 (random), version 7 (time-ordered), version 1 (timestamp), or the special Nil and Max values, following RFC 9562.
How to use UUID Generator
- Choose the Version (version 4 is the usual choice; version 7 for database keys).
- Set How many UUIDs you need.
- Optionally tick Uppercase, untick Hyphens, or tick Wrap in braces { }.
- Click Regenerate for a new batch, then copy or download the list.
Example
Version 7, How many 2
01a16811-eb97-7688-838a-aa989505507e 01a16811-eb97-7689-a2db-f00f7ac48f06
Both start with the same millisecond timestamp; the counter makes the second sort after the first. Your values will differ.
When to use UUID Generator
Use v4 for general unique IDs (API resources, file names, correlation IDs). Use v7 for database primary keys, because time-ordered values keep B-tree indexes compact. Avoid v1 unless a system requires it, and never use UUIDs as secrets or access tokens: they are unique, not secret.
How UUID Generator works
v4: 16 random bytes from crypto.getRandomValues; the version nibble is set to 4 and the two variant bits to 10, leaving 122 random bits. v7: the first 48 bits are the current Unix time in milliseconds (big-endian), followed by the version, a 12-bit counter (so UUIDs created in the same millisecond still sort in order) and 62 random bits. v1: a 60-bit count of 100-nanosecond intervals since 15 October 1582, a 14-bit clock sequence and a 48-bit node ID; the tool uses a random node with the multicast bit set (as RFC 9562 allows) instead of your MAC address. The embedded timestamp of v1/v7 is decoded and shown below the list.
Common Use Cases
- Creating primary keys for database rows or test fixtures
- Generating request or correlation IDs for logs
- Naming uploaded files without collisions
- Seeding mock data with unique identifiers
FAQs
Can two UUID v4 values collide?
In theory yes, in practice no: with 122 random bits you would need to generate about 2.7 × 10^18 UUIDs to have a 50% chance of a single duplicate.
What is the difference between UUID v4 and v7?
v4 is fully random. v7 starts with a timestamp, so values created later sort after earlier ones, which is better for database indexes and lets you read the creation time.
Is a UUID the same as a GUID?
Yes. GUID is Microsoft's name for the same 128-bit format. Use the GUID generator for Windows-specific formats such as registry braces.
Does v1 reveal my MAC address?
Not here. The node field is filled with random bytes and the multicast bit is set to mark it as non-hardware.