UUID Generator

Generate version 4 UUIDs instantly in your browser

A UUID generator creates universally unique identifiers — 128-bit values that let independent systems label data without ever coordinating with one another. Our free tool produces cryptographically strong version 4 UUIDs directly in your browser, so you can spin up a single identifier or a batch of thousands in an instant. Because generation uses the secure crypto.getRandomValues API, every value carries 122 bits of randomness and is effectively guaranteed to be unique.

Developers reach for UUIDs constantly: as database primary keys that can be generated on the client, as correlation IDs that stitch together logs across microservices, as idempotency keys for safe API retries, and as collision-free file or session names. Generating them by hand is impractical, and copying from unreliable sources risks duplicates. This tool removes that friction with clean, well-formatted output and flexible options for case and formatting.

Everything runs locally with no uploads and no accounts, so the identifiers you create stay entirely on your device. Choose how many you need, toggle uppercase or hyphen removal to match your schema, then copy an individual value, copy the whole list, or download it as a text file. It is a fast, private, dependable way to produce the identifiers your applications rely on.

Why use UUID Generator?

Cryptographically secure

Uses the browser's crypto.getRandomValues API, giving 122 bits of randomness and collision probabilities too small to matter in practice.

Bulk generation

Create a single UUID or thousands at once, then copy the whole batch or download it as a text file in one click.

Flexible formatting

Toggle uppercase output or strip hyphens to match your database schema, API contract, or file-naming convention.

Generated in your browser

All UUIDs are generated locally in your browser and are not sent to a ToolsGuru server.

How to use UUID Generator

1
Set the quantity
Enter how many UUIDs you need, from one to several thousand, using the count input.
2
Choose formatting options
Optionally switch to uppercase or remove hyphens to fit your target system's requirements.
3
Generate
Click Generate and the full list of version 4 UUIDs appears instantly, ready to use.
4
Copy or download
Copy any single UUID, copy the entire list to your clipboard, or download everything as a .txt file.

Common use cases

Database primary keys

Generate client-side keys for records so systems can insert data without waiting on a central sequence, ideal for distributed and offline-first apps.

API request tracing

Attach a UUID as a correlation or idempotency key to safely retry requests and follow a single operation across microservices and logs.

Unique file and asset names

Name uploads, exports, and temporary files with UUIDs to eliminate naming collisions in shared storage buckets.

Test and seed data

Quickly fabricate large sets of unique identifiers for load testing, fixtures, or seeding a development database.

Worked example: Client-side IDs for a village fete volunteer roster

A volunteer app stored shifts in SQLite on each steward’s phone before syncing. They generated 40 UUID v4 values in the browser, copied them into a seed file, and assigned each to a shift row (`gate-am`, `tea-tent-pm`, and so on). Because IDs existed before sync, two people adding a ‘lost child’ note offline did not collide.

They kept hyphens on because the ORM expected the 8-4-4-4-12 shape. Uppercase was off — PostgreSQL would fold it anyway. This is not a password; the UUIDs were identifiers, visible in logs on purpose.

Limitations

This page generates UUID version 4 (random). It is not UUID v1 (time-MAC), v5 (name-SHA-1), or ULID/KSUID.
Uniqueness is statistical. Do not use a UUID as a secret capability URL unless you also enforce auth — guessing is hard, leaking the URL is easy.
Bulk thousands is fine; millions belong in a script, not a textarea.
It will not register IDs with a central authority. There is none.

When not to use UUID Generator

Do not use UUIDs as passwords or encryption keys. Use the password generator or a real KMS.
If your database already uses autoincrement and you have no distribution problem, adding UUIDs just to look modern can hurt index locality.
Regulated ID schemes (NHS numbers, invoice legal sequences) are not UUIDs. Follow the scheme.

Features at a glance

Version 4 (random) UUID generation
Cryptographically secure randomness via crypto.getRandomValues
Bulk generation of one to thousands at once
Uppercase output toggle
Optional hyphen removal
Copy a single UUID with one click
Copy the entire list to the clipboard
Download all UUIDs as a text file

Frequently asked questions

What is a UUID and how is version 4 different?

A UUID (Universally Unique Identifier) is a 128-bit value used to identify information uniquely across systems without a central authority. Version 4 UUIDs are generated from random or pseudo-random numbers rather than timestamps or MAC addresses. This makes them ideal for privacy-sensitive use because they reveal nothing about the machine or time that created them.

Are the UUIDs generated by this tool truly unique?

Version 4 UUIDs use 122 bits of randomness, giving roughly 5.3 x 10^36 possible values. The probability of generating a duplicate is astronomically small — you would need to create billions of UUIDs per second for many years before a collision became likely. For practical purposes they are treated as guaranteed unique.

Does this UUID generator send data to a server?

No. Every UUID is generated locally in your browser using the cryptographically secure crypto.getRandomValues API. Nothing is sent to a ToolsGuru server, so the identifiers you create stay on your device.

Can I generate many UUIDs at once?

Yes. Enter the number of UUIDs you need — from one to thousands — and the tool produces the whole batch instantly. You can then copy an individual value or copy the entire list to your clipboard in one click, or download them as a text file.

What are common uses for UUIDs?

UUIDs are widely used as database primary keys, API request identifiers, distributed system correlation IDs, file names, session tokens, and message identifiers. They let independent systems generate keys without coordinating with each other, which prevents collisions in distributed and offline-first applications.

Your privacy matters

UUID Generator is designed to run in your web browser. File and text tools process bytes in memory on your device rather than uploading them to a ToolsGuru converter API. Network requests you still see are the page itself, analytics, and ads — not a copy of your document sitting in our logs. How we process files, and how to check.