UUID / GUID Generator
Generate random version-4 UUIDs, using your browser's cryptographically secure random generator.
How to Generate UUIDs
- Enter how many UUIDs you want (1 to 100) in the "How many?" field.
- Choose lowercase or UPPERCASE letters, and whether to include hyphens, from the two dropdowns.
- Click "Generate" to produce the list.
- Copy one UUID with its row's "Copy" button, or click "Copy All" to copy the whole list at once, one per line.
Frequently Asked Questions
What version of UUID does this generate?
Version 4 — a randomly generated UUID as defined by RFC 4122, where the version and variant bits are set rather than derived from a MAC address or timestamp like version 1, so each ID is effectively random rather than sequential or traceable to your machine.
How is the randomness actually generated?
The tool first tries crypto.randomUUID(), a built-in browser method for generating RFC-compliant v4 UUIDs. If that isn't available, it falls back to manually building one from 16 random bytes pulled from crypto.getRandomValues() and setting the version and variant bits by hand.
What do the letter case and format options change?
They only affect how the UUID is displayed — uppercase versus lowercase letters, and whether hyphens are included between the groups. The underlying 128-bit random value and its uniqueness are identical either way.
Can two generated UUIDs collide?
In practice, no. With 122 random bits in a v4 UUID, the probability of ever generating a duplicate is astronomically small, which is why UUIDs are widely used as unique identifiers for database rows and API resources without checking for collisions.
Is there a limit to how many UUIDs I can generate at once?
Yes — the count field accepts 1 to 100 per click; entering a higher number is automatically capped at 100.