How it works

Generate one or up to 1000 UUID v4 IDs at a time, in lowercase, uppercase, no-hyphens, or {braces} format.

Built on crypto.randomUUID, the browser's standard cryptographically-secure UUID v4 generator. Set the quantity (1 to 1000) and pick a format: default (lowercase with hyphens, e.g. 550e8400-e29b-41d4-a716-446655440000), uppercase, no hyphens (550e8400e29b41d4a716446655440000, for compact storage), or {braces} (Windows GUID style, {550e8400-e29b-41d4-a716-446655440000}). The output is one UUID per line, ready to copy. UUID v4 uses 122 bits of randomness, giving a collision probability so vanishingly small (1 in 2^61 for a billion IDs generated by the same source) that it's safe to use as a primary key across distributed systems without coordination.

How to use it

1. Set the quantity. Generate 1 to 1000 UUIDs at once.
2. Pick a format. Lowercase with hyphens, UPPERCASE, no hyphens, or {braces} Windows GUID style.
3. Generate and copy. One UUID per line, produced by the browser's CSPRNG — safe for keys and tokens.

Frequently asked questions

What's UUID v4?

A 128-bit identifier with 122 bits of pure randomness. Version 4 means it's random (not derived from time or namespace). The collision probability is negligible at any practical scale.

Are they cryptographically secure?

Yes. crypto.randomUUID uses the browser's CSPRNG. Safe for use as opaque identifiers, session tokens, and primary keys.

Can I generate UUID v1, v5, or v7?

Not in this tool. Only v4. v1 (time-based) and v5 (namespace-based) are less commonly used; v7 (time-sortable) isn't widely supported in browsers yet.

Are the UUIDs uploaded?

No. Generated locally via the browser's Web Crypto API.