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UUID Generator

Generate RFC 4122 v4 UUIDs in bulk - crypto-secure, uppercase and no-hyphens modes, copy or download.

By Mubeen Khan · Last reviewed 2026-10-19

Press Generate to create UUIDs.

🔒 Privacy: UUIDs are generated locally in your browser with crypto.randomUUID(), a cryptographically secure source. Nothing is uploaded or stored.

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How this calculator works

A UUID, universally unique identifier, is a 128-bit value formatted as 36 characters like 550e8400-e29b-41d4-a716-446655440000. Version 4 UUIDs are generated from random bits, which makes collisions so unlikely you can hand them out as database primary keys, order IDs, API tokens or test identifiers without coordinating with anyone first. Press Generate and you get 10 by default; switch the count up to 500 for bulk test data.

Two options cover the common formatting needs. Uppercase mode renders A-F digits in capitals for systems that expect it, and no-hyphens mode strips the four dashes to produce the 32-character compact form some APIs and databases prefer. Every UUID is produced with crypto.randomUUID(), the browser's cryptographically secure random source, not the predictable Math.random(), so they are safe to use as unguessable identifiers.

Bulk mode is the long-tail hook this tool is built around. Seeding a database, writing integration tests, or generating 500 sample order IDs takes one click, then Copy all or Download .txt hands the list to your script or migration file. Pair it with the JSON Formatter when you need to embed fresh IDs into test payloads, everything runs locally in your browser and nothing is ever uploaded or stored.

Frequently asked questions

What is a UUID?
A UUID (universally unique identifier) is a 128-bit value written as 36 characters, for example 550e8400-e29b-41d4-a716-446655440000. Version 4 UUIDs are generated from random bits and are used as database primary keys, order IDs, API tokens and test identifiers.
Are these UUIDs truly random?
Yes. They are generated with crypto.randomUUID(), the browser's cryptographically secure random source, not the predictable Math.random(). That makes them suitable as unguessable identifiers.
What is the difference between UUID and GUID?
They are the same 128-bit format. GUID (globally unique identifier) is just Microsoft's name for a UUID. A v4 UUID from this tool works anywhere a GUID is accepted.
Should I use uppercase or lowercase UUIDs?
The RFC does not care, but pick one form and stick with it. Lowercase is the common convention in JSON APIs and URLs; some legacy systems and databases expect uppercase. The tool has a one-click uppercase mode.
Why would I remove the hyphens?
Some APIs, databases and URL schemes expect the compact 32-character form without dashes. No-hyphens mode strips them for you; the value identifies the same UUID either way.
Can two UUIDs collide?
In practice, no. With 122 random bits, you would need to generate about 2.7 quintillion UUIDs to reach a 50% chance of a single collision. For everyday use, uniqueness is effectively guaranteed.

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Disclaimer: Results are estimates for planning purposes only and are not financial advice. Actual loan terms, taxes and investment returns vary. Consult a qualified professional before making financial decisions.