UUID / GUID Generator

Cryptographically secure identifiers generated locally on your device.

V4 Random

Settings

Version

Number of UUIDs

Max 100

Include Hyphens

Standard 8-4-4-4-12 format

Uppercase Output

A-F vs a-f characters

What is a UUID / GUID?

A Universally Unique Identifier (UUID) or Globally Unique Identifier (GUID) is a 128-bit label used for information in computer systems. Version 4 UUIDs are generated using random or pseudo-random numbers, ensuring the probability of a duplicate is practically zero.

Hardware-Level Cryptography

ZeroServer utilizes your browser's native crypto.randomUUID() API. This ensures that every identifier is generated using mathematically secure, hardware-backed entropy, making it perfectly safe for database keys and secure session IDs.

Frequently Asked Questions

What is a UUID?

A Universally Unique Identifier is a 128-bit number formatted as 8-4-4-4-12 hex digits (e.g. 550e8400-e29b-41d4-a716-446655440000). They can be generated independently on any machine with an astronomically low collision probability.

What's the difference between UUID v4 and v7?

v4 is entirely random — ideal for most use cases. v7 embeds a millisecond timestamp in the top bits, making it time-ordered. v7 is better for database primary keys as it maintains insertion order and improves B-tree index performance.

Are UUIDs guaranteed to be unique?

Not mathematically guaranteed, but the collision probability for v4 is roughly 1 in 10^36 per pair — effectively impossible in practice. v1 and v7 use time-based components that further reduce collision risk.

Should I use UUIDs or auto-increment IDs in my database?

UUIDs are better when you generate IDs client-side (before insert), merge multiple data sources, or need to avoid exposing sequential record counts. Auto-increment IDs are smaller, faster to index, and simpler for single-database apps.

How should I store UUIDs in a database?

Use the native UUID type in PostgreSQL, or BINARY(16) in MySQL for the best performance. VARCHAR(36) works but wastes storage and slows index lookups compared to a native 16-byte binary type.

Private & free — this tool runs entirely in your browser.