UUID Generator

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit identifier designed to be unique across space and time without any central coordination. It is written as 32 hexadecimal digits in five hyphen-separated groups, for example 550e8400-e29b-41d4-a716-446655440000. Version 4 UUIDs are generated from random numbers.

Our UUID Generator uses the browser's cryptographically secure random number generator (crypto.randomUUID), so the values are suitable for production use as database keys, request identifiers, and more. The probability of a collision between two v4 UUIDs is so vanishingly small it can be treated as zero in practice.

How to Generate UUIDs

• Use the slider to choose how many UUIDs to generate, up to 50 at once
• Toggle Hyphens off to produce a compact 32-character form
• Toggle Uppercase to get uppercase hexadecimal digits
• Click Regenerate or New set for a fresh batch of random values
• Copy a single UUID, or use Copy all to grab the whole list

Common Uses for UUIDs

Developers use UUIDs as primary keys in databases (especially distributed ones where auto-incrementing integers cause conflicts), as identifiers for API requests and log correlation, as filenames for uploaded assets, and as session or transaction IDs. Because they can be generated independently on any machine without coordination, they are ideal for distributed systems.

UUIDs also avoid the information leakage of sequential IDs — they do not reveal how many records exist or allow easy guessing of other identifiers, which is a useful privacy and security property.

Privacy

Every UUID is generated locally in your browser using the secure crypto API. Nothing is sent to or stored on a server, so the identifiers are private to you.

Why Version 4 UUIDs?

There are several versions of UUID, each generated differently, but version 4 — the random variant — is by far the most widely used in application development. A v4 UUID is built almost entirely from random bits, with a few reserved to mark the version and variant. This means it carries no embedded information: unlike time-based or MAC-address-based versions, it does not reveal when or where it was created, which is a useful privacy property.

The randomness is what makes v4 UUIDs practical to generate anywhere without coordination. Two systems, or two thousand, can mint identifiers independently and never collide in practice, because the space of possible values — roughly 5.3 undecillion — is so vast. Our generator draws that randomness from the browser's cryptographically secure crypto.randomUUID, so the values are robust enough for real production use, not just toy examples.

Why Choose Our UUID Generator?

This generator is completely free, needs no signup, and runs entirely in your browser. It uses the browser's cryptographically secure random source rather than a weak pseudo-random shortcut, so the UUIDs are suitable for database keys and other production uses. You can generate up to 50 at once and tune the format — hyphens on or off, lowercase or uppercase — to match exactly what your system expects.

The UUID Generator is one of more than 200 free tools on ToopTools. If you need identifiers often, you can pin it to your personalized My Workspace workspace so it sits beside your other developer utilities, always one click away. It works on any modern browser, on desktop and mobile.

Is the UUID generator free?

Yes. It is completely free with no limits and no signup. You can generate as many UUIDs as you like, as often as you like, without ever creating an account.

Are these UUIDs safe for production use?

Yes. The tool uses crypto.randomUUID, the browser's cryptographically secure generator, to produce standards-compliant version 4 UUIDs. They are suitable for database primary keys, request identifiers, file names, and any other production use where a unique identifier is needed.

Could two generated UUIDs ever collide?

In practice, no. A version 4 UUID has 122 random bits, giving around 5.3 undecillion possible values. The probability of generating the same one twice is so astronomically small that it is treated as zero in real systems, which is exactly why UUIDs can be created independently without central coordination.

Can I generate UUIDs without hyphens or in uppercase?

Yes. Toggle Hyphens off to get a compact 32-character form with no dashes, and toggle Uppercase to produce uppercase hexadecimal digits. These options let you match the exact format your database, API, or file-naming convention requires.

What is the difference between a UUID and a GUID?

None in practice. GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier standard; UUID is the term used elsewhere. They have the same format and are interchangeable, so a v4 UUID from this tool works anywhere a GUID is expected.

Common Uses for UUIDs

• Primary keys in databases, especially distributed systems where auto-increment IDs clash
• Correlation IDs for tracing a request across logs and services
• Unique file names for uploads to avoid collisions
• Session, transaction, and idempotency keys
• Any identifier you want to generate client-side without a round trip to the server

Key Features

• Cryptographically secure version 4 UUIDs via the browser's crypto API
• Generate up to 50 identifiers in a single batch
• Toggle hyphens for the standard or compact 32-character form
• Toggle uppercase or lowercase hexadecimal
• Copy a single UUID or the whole list at once
• 100% browser-based — nothing is sent to a server

UUIDs vs Auto-Increment IDs

Traditional databases assign primary keys with an auto-incrementing integer: 1, 2, 3, and so on. That works well on a single server, but it creates problems at scale. Two database nodes cannot both mint the 'next' integer without coordinating, which becomes a bottleneck in distributed systems, and sequential IDs leak information — anyone can see roughly how many records exist and guess neighbouring identifiers just by adding or subtracting one.

UUIDs solve both issues. Because each value is effectively random and globally unique, any service or device can generate one independently with no central counter, which is ideal for distributed architectures, offline-first apps, and merging data from multiple sources. They also reveal nothing about volume or order, removing the enumeration risk of sequential keys. The trade-off is that UUIDs are larger and not naturally sortable, so the choice depends on whether distribution and opacity matter more than compactness for your use case.

How do I generate multiple UUIDs at once?

Set how many UUIDs you want and the tool generates them all instantly using your browser's cryptographically secure randomness. You can output them without hyphens or in uppercase, then copy the whole list in one click for use as IDs or keys.

Does the UUID generator work offline?

Yes. UUIDs are generated entirely in your browser, so once the page has loaded the tool works without an internet connection and nothing is sent to a server. The values are created locally on your device, so they stay private to you.