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UUID Generator

Generate UUIDs in multiple versions, formats and language-specific output snippets.

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Format Examples

Standard:550e8400-e29b-41d4-a716-446655440000
Uppercase:550E8400-E29B-41D4-A716-446655440000
No Dashes:550e8400e29b41d4a716446655440000
With Braces:{550e8400-e29b-41d4-a716-446655440000}

About UUIDs

Version 1 (Timestamp): Generated from current timestamp and node ID. Useful when you need time-ordering or want to know when a UUID was created.
Version 4 (Random): Randomly generated using cryptographically strong random number generator. Most commonly used version. Safe for all general purposes.
NIL UUID: Special UUID consisting of all zeros (00000000-0000-0000-0000-000000000000). Used as a placeholder or to represent null.
MAX UUID: Special UUID consisting of all Fs (ffffffff-ffff-ffff-ffff-ffffffffffff). Useful for testing or as a boundary value.

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hex digits in 5 groups: 550e8400-e29b-41d4-a716-446655440000. UUIDs are designed to be globally unique without a central authority. Tip: UUID v4 (random) is the most commonly used version for general-purpose IDs.

What are the differences between UUID versions?

v1: timestamp + MAC address (reveals creation time). v4: fully random (most popular). v5: SHA-1 hash of a namespace + name (deterministic). v7: timestamp-ordered random (new, sortable). Tip: use v4 for most cases, v7 when you need time-sortable IDs (great for database primary keys).

Can UUIDs collide?

Theoretically yes, but the probability is astronomically low. With UUID v4, you'd need to generate 2.71 quintillion UUIDs to have a 50% chance of one collision. Tip: for practical purposes, treat UUID v4 as unique. If you're generating billions of IDs, consider UUID v7 which adds a timestamp prefix.

Should I use UUID or auto-increment IDs?

Auto-increment IDs are simpler and smaller but reveal record count and creation order. UUIDs are larger (16 bytes vs 4-8) but work in distributed systems without coordination. Tip: UUID v7 combines the best of both — it's globally unique, sortable by creation time, and works across distributed databases.

What is a ULID and how does it compare?

ULID (Universally Unique Lexicographically Sortable Identifier) is similar to UUID v7: 128 bits with a timestamp prefix for sortability, encoded as a 26-character Crockford Base32 string. ULIDs are URL-safe and sort correctly as strings. Tip: choose UUID for broad ecosystem compatibility; ULID for compact, sortable string IDs.