UUID Generator

Generate UUID v1 (time-based), v4 (cryptographically random), or v5 (SHA-1 name-based) — one at a time or in bulk. Output in standard, UPPERCASE, no-hyphens, or braces format. One-click copy. Pro: generate up to 100 at once.

Frequently Asked Questions

What is a UUID and when should I use one?▼

A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. Use UUIDs as primary keys in databases, session tokens, API request IDs, or any time you need a unique identifier without a central authority.

What is the difference between UUID v1, v4, and v5?▼

UUID v1 is time-based (includes timestamp and MAC address). UUID v4 is completely random using cryptographic randomness — the most common choice. UUID v5 is deterministic, generated from a namespace and a name using SHA-1, so the same inputs always produce the same UUID.

Is UUID v4 truly unique?▼

Practically yes. UUID v4 has 122 random bits, giving 5.3 × 10^36 possible values. The probability of a collision is astronomically low — you'd need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of one duplicate.

What is the difference between UUID and GUID?▼

They are the same thing. UUID is the official term from RFC 4122. GUID (Globally Unique Identifier) is Microsoft's name for the same concept. Both use the same 8-4-4-4-12 hex format.

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