UUID generator — version 4 and version 7
Generate up to 500 UUIDs for records, fixtures or other identifiers. Choose random v4 IDs or timestamp-prefixed v7 IDs, then copy the batch in the format your system accepts.
Runs in your browser — your input is not uploaded to ToolsNow.
The usual choice. 122 bits of randomness, no ordering.
1 to 500
How to use
- Choose UUID version. Use Version 4 — random for general identifiers, or Version 7 — time-ordered if your system expects v7.
- Set How many. Enter a whole number from 1 to 500. Changing the count or version generates a new batch, so copy any IDs you need first.
- Format and copy. Choose UPPERCASE, Remove hyphens or Wrap in {braces} if required. Copy all takes one ID per line; Generate again creates a fresh batch.
Questions
How should I choose between v4 and v7?
v4 contains random bits without a creation timestamp. v7 starts with the device’s current Unix time in milliseconds, which can help keep nearby inserts together in a database index. Check your database and application’s UUID support; v7 is not a promise of faster queries.
Will v7 IDs sort in the exact order I generated them?
Not necessarily. This implementation fills the rest of each ID randomly, with no sequence counter. IDs made in the same millisecond can sort in a different order, and a clock adjustment can affect ordering. The timestamp also reveals the approximate generation time.
Can two generated UUIDs match?
Yes, although a collision between properly generated random UUIDs is very unlikely. v4 has 122 random bits supplied by crypto.getRandomValues. Keep a uniqueness constraint where duplicate IDs would cause a problem; random generation is not a database check.
Can I use a UUID as an access token?
Use a token mechanism designed for authentication instead. UUIDs are identifiers that often appear in logs and URLs, and v7 exposes a timestamp. Cryptographic randomness does not make an identifier an access-control system.
What are Nil UUID and Max UUID?
Fixed values containing all zeroes or all ones. They can serve as sentinels, such as an empty-value marker or upper bound. They are not unique IDs, so generating several gives the same value repeatedly.
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