Calzivo

Browser-generated identifiers

UUID Generator

Create one or up to 100 lowercase UUID v4 identifiers using secure browser randomness, then copy raw values or download the ordered list.

Generate UUID v4 values

Enter a whole number from 1 to 100. Leading zeroes are accepted.

UUID v4 result

No UUIDs generated

Enter a count and generate explicitly. Nothing is generated on page load.

How UUID v4 is formed

Each UUID starts with 16 cryptographically random bytes. The version nibble is set to 4 and the RFC variant bits are set before lowercase hexadecimal formatting in the standard 8-4-4-4-12 shape.

For example, bytes 00 through 0f become 00010203-0405-4607-8809-0a0b0c0d0e0fafter version and variant masking.

Individual Copy uses only the raw UUID. Copy All and the text download preserve generation order with LF separators and no trailing newline.

Privacy and limitations

UUID v4 values are generated in this browser using cryptographically secure browser randomness. This tool does not send generated values to a generation server.

Collisions are extremely unlikely but not impossible. Keep uniqueness constraints where they matter. UUIDs are identifiers, not passwords, access tokens, or encryption keys.

Common mistakes

  • Treating an identifier as an authentication secret.
  • Removing hyphens when another system expects RFC formatting.
  • Assuming low collision probability replaces a database constraint.
  • Expecting UUID v4 values to sort by creation time.

FAQs and standards

Can I generate in bulk? Yes, from 1 through 100 values per explicit generation.

Are duplicates retried? No. A duplicate within one batch fails the complete batch visibly.

Standards: RFC 9562 and Web Crypto getRandomValues().