UUID Generator

How to use

1. Choose how many UUIDs you need.
2. Click Generate — they appear instantly.
3. Copy all with one click.

About this tool

Version 4 UUIDs are randomly generated — the chance of two colliding is astronomically small.

They are created with your browser’s cryptographic random generator and never touch a server.

How it works

A UUID (Universally Unique Identifier) is a 128-bit value written as 32 hexadecimal digits in five groups — 8-4-4-4-12, like 550e8400-e29b-41d4-a716-446655440000. This tool generates version 4 UUIDs: 122 of the 128 bits are random, and the other 6 are fixed markers — the 13th digit is always 4 (the version) and the 17th is 8, 9, a, or b (the variant), as defined in RFC 4122 (updated by RFC 9562).

Because the random space holds 2^122 possibilities, you would need to generate about a billion UUIDs per second for 85 years before reaching even a 50% chance of one collision. That is why UUIDs are safe to mint locally with no central registry — two systems will essentially never pick the same value by accident.

UUIDs are the default choice for database primary keys, session tokens, idempotency keys, and upload filenames. Version 4 fits whenever you just need a unique random identifier; version 1 (time-based) or the newer version 7 (time-ordered random) are worth a look only if you need IDs that sort chronologically.

Worked examples

Database primary key: Instead of auto-incrementing integers that reveal how many rows you have, use a UUID as the primary key: INSERT INTO orders (id, total) VALUES ('a3bb189e-8bf9-4e5a-9c1d-2f3a7b6c9d01', 49.99). Clients can generate the ID before inserting, which also simplifies offline-first apps.

Collision-free upload filenames: When a user uploads profile.jpg, store it as 7e4f2a1c-9b3d-4e8f-a2c5-6d7e8f9a0b1c.jpg and filename collisions become impossible — no existence check needed before saving.

Quick reference

Frequently asked questions

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