A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify objects in software systems. The standard format is 8-4-4-4-12 hexadecimal characters (e.g., 550e8400-e29b-41d4-a716-446655440000).

What is the difference between UUID v4 and v1?

UUID v4 is randomly generated — it has no relationship to the machine or time it was created on, making it suitable for most purposes. UUID v1 is time-based and includes the MAC address of the generating machine, which has privacy implications.

Are generated UUIDs truly unique?

UUID v4 uses 122 bits of randomness. The probability of generating two identical UUIDs is approximately 1 in 5.3×10^36 — effectively zero for any practical use case.

⚡ UUID v4 · Browser-Side · Instant

UUID Generator

Generate RFC 4122 compliant UUID v4 identifiers instantly. Bulk generate, format options, copy-all in one click.

Generate UUIDs

Click Generate to create UUIDs

📋 What is UUID v4?

UUID v4 uses random data to create a 128-bit identifier. Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" and "y" bits are fixed per the RFC 4122 spec.

🎲 Collision Probability

With 2¹²² possible values, the chance of a collision is astronomically small. You'd need to generate a billion UUIDs per second for 85 years to have a 50% collision chance.

🔒 Browser-Side Only

Generated using crypto.randomUUID() (with fallback). Nothing is sent to any server — these are yours alone.

UUID Generator — FAQ

What's the difference between UUID and GUID?

They're the same thing. GUID (Globally Unique Identifier) is Microsoft's term for UUID. Both follow the same RFC 4122 specification and produce identical-format identifiers.

Is UUID v4 suitable for database primary keys?

Yes, but consider UUID v7 for databases — it's time-ordered so it creates less index fragmentation. UUID v4 is ideal for session tokens, API keys, correlation IDs, and any case where unpredictability matters.

Are these UUIDs safe to use in production?

Yes. This tool uses your browser's cryptographically secure random number generator (crypto.randomUUID()), the same source used in production security software.