UUID Generator: Create UUID v4 IDs Instantly

Tooly · 2026-08-02 · 4 min read

Databases, APIs, and distributed systems all need unique identifiers — and UUIDs are the standard answer. A UUID generator creates them instantly, in any quantity, so you can seed your database or test your API without copy-pasting from a terminal. The good ones run entirely in your browser.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit value formatted as 8-4-4-4-12 hex digits — like f47ac10b-58cc-4372-a567-0e02b2c3d479. Version 4 is random-based, which means collisions are astronomically unlikely, making it the default for most applications.

Generate UUIDs free with Tooly

The Tooly UUID Generator does it right:

Generate UUID v4 IDs in bulk — one click or a hundred
Copy any single ID or the whole list
Runs in your browser — nothing is uploaded
Free, no signup, no watermark

Generate UUIDs free — no signup
Open UUID Generator

When you'll use it

Seeding database records and migrations
Generating test data for APIs and integrations
Creating unique keys for distributed systems
Building demo apps and mock payloads

UUID vs. auto-increment IDs

UUID v4	Auto-increment
Unique across systems (no coordination)	Unique only within one database
Safe to expose in URLs/APIs	Enumerability can leak data
Slightly larger storage	Compact integers
Great for distributed/microservices	Simplest for tiny single-server apps

Frequently Asked Questions

Is this UUID generator really free? Yes — unlimited generation, no account, no watermark.

Can two UUIDs collide? v4 generates 122 random bits — collision odds are effectively zero for real-world workloads.

Is my input uploaded? There's no input — generation is entirely client-side, so nothing leaves your browser.

What pairs well with it? The JSON Formatter for payloads and Base64 for encoding are favorite companions.

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