How to use the uuid generator (v4 and v7)
- Choose v4 (random) or v7 (time-ordered).
- Enter how many you need, from 1 to 1,000.
- Set formatting: uppercase, braces, or no hyphens.
- Copy all or download them as a .txt file. Select Generate for a fresh batch.
- Paste any UUID into the validator to check it and see its version, variant and embedded timestamp.
Worked example
Reading a v7 timestamp
The RFC 9562 example 017f22e2-79b0-7cc3-98c4-dc0c0c07398f is detected as version 7, RFC 9562 variant, and its first 48 bits decode to 2022-02-22 19:22:22 UTC. A new v7 UUID generated now starts with the current Unix time in milliseconds, so IDs sort by creation time.
How it works
v4 uses crypto.randomUUID(), or 16 bytes from crypto.getRandomValues() with the version and variant bits set. v7 follows RFC 9562 section 5.7: a 48-bit big-endian millisecond timestamp, version 7, a 12-bit counter seeded randomly for each new millisecond (section 6.2, method 1) so a batch is strictly increasing, the 10 variant bits and 62 random bits.
Frequently asked questions
Is my data uploaded?
No. This tool runs entirely in your browser. Your input is processed on your device and is not sent to our server or stored.
Should I use v4 or v7?
v7 suits database primary keys because new IDs sort after old ones, which keeps B-tree indexes compact. v4 reveals nothing about when it was created, which is better when the ID is public and timing should stay private.
Can two generated UUIDs collide?
In practice no. v4 has 122 random bits; you would need about 2.7 quintillion IDs for a 50% chance of one collision. v7 adds the timestamp, so collisions would also need the same millisecond.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit format. Microsoft tools often show GUIDs in uppercase with braces, which you can switch on here.
Limitations
- v1, v3, v5, v6 and v8 are recognised by the validator but not generated.
- v7 ordering is guaranteed within one batch; across devices it depends on each device clock.