UUID Generator (v4)

Cryptographically random version-4 UUIDs, single or in bulk - generated locally in your browser.

Bulk amount 1 – 500
10
Uppercase
Without hyphens

Anatomy of a UUID

Those 36 characters aren't all random - Two positions are reserved:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

  • The 4 in the third group is the version digit - It tells parsers "this is a random UUID."
  • The y position holds the variant bits - Always 8, 9, a or b for standard UUIDs. Spot a v4 UUID with a different digit there and it wasn't generated correctly.
  • Everything else - 122 bits - Is pure CSPRNG output.

That version digit is also a quick forensic tell: a 1 means timestamp+MAC (leaks when and where it was made), a 7 means timestamp-prefixed, a 4 means fully random.

About Version-4 UUIDs

122 bits of randomness

A v4 UUID contains 122 random bits (6 bits are fixed for version and variant). The collision odds are absurd: you'd need to generate a billion UUIDs per second for about 85 years to reach a 50% chance of one duplicate.

This page uses crypto.randomUUID() - The same CSPRNG machinery behind our password generator.

Common uses

  • Database primary keys and API resource IDs.
  • Idempotency keys for payment APIs.
  • Correlation IDs in distributed tracing.
  • Anywhere an unguessable identifier matters - Though for secrets, prefer a real passphrase or random token.

How to Use the UUID Generator

1

Generate one or many

The single UUID refreshes on demand; bulk mode produces up to 500 at once.

2

Pick formatting

Uppercase or hyphen-free variants for systems with specific format rules.

3

Download the list

Bulk lists export as a plain .txt, one UUID per line.

UUID versions - What each is based on

VersionBased onRandom bitsWhen to use
v1Timestamp + MAC address14Legacy; leaks time and hardware identity
v4Pure randomness122The default - What this tool generates
v5SHA-1 of a name0 (deterministic)Stable IDs derived from names
v7Timestamp + randomness74Database keys needing sortable order

UUID Generator - FAQ

Can two v4 UUIDs ever collide?
In theory; in practice, no. With 122 random bits you'd need to generate a billion UUIDs per second for roughly 85 years to reach a 50% chance of a single collision.
Are these UUIDs safe to use as secret tokens?
A v4 UUID from a CSPRNG (like this page's crypto.randomUUID) is unguessable, so it works as a capability token. But purpose-built secrets - API keys, session tokens - Usually want more bits and a format that survives redaction tools; a 32-character random string is better.
Are version-4 UUIDs sortable?
No - They're fully random, so insertion order and sort order have no relationship. If you need time-ordered IDs (for pagination or clustered indexes), that's exactly what UUID v7 adds with its timestamp prefix.
Should I use v4 or v7 for database primary keys?
v7 if your database suffers from index fragmentation with random keys - Its timestamp prefix keeps inserts ordered. v4 if key unpredictability matters more than insert locality.

More questions about passwords and security? Browse the security guides.

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