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UUID Generator

Generate UUID v4 (RFC 4122) identifiers online, one or up to 50 at once, with capitalization option and copy button.

What is it

UUID (Universally Unique Identifier) is a code designed to name records, files and other resources in a unique way, without depending on a central server to avoid repetition. In practice, it appears as a 36-character sequence in the format 8-4-4-4-12, separated by hyphens, as in 550e8400-e29b-41d4-a716-446655440000. On some platforms, mainly in the Microsoft ecosystem, the same concept is called GUID (Globally Unique Identifier), but it is the same type of code.

There are several versions of UUID, defined by RFC 4122. This generator creates the version most used in everyday systems: the UUID v4, assembled from random numbers. It is generated with the browser's own Web Crypto API (the crypto.randomUUID() method), a cryptographically secure randomization feature. With 122 bits of entropy available, the chance of two UUID v4 coming out the same is so low that, in practice, each code can be treated as unique, even generating billions of them.

Programmers, system administrators, and computer science students use UUID for database primary keys, API keys, session IDs, file names, correlation of events in queues and logs, and test data wherever a unique identifier is needed without consulting a central server before creating the record.

How to use

Generating one or several v4 UUIDs takes just a few seconds:

  • Choose quantity: define how many codes you want to generate at once, from 1 to 50.
  • Enable capital letters, if necessary: check the option to receive the result with capital letters, if your system or code convention requires this pattern.
  • Click on Generate UUID: the codes appear instantly, calculated directly in the browser.
  • Copy what you need: use the copy button on each line or, when generating more than one, the "Copy all" button to take the entire list at once, one UUID per line.

All processing happens on your device, without sending anything to external servers.

Good practices for developers

  • UUID v4 is random, not sequential. If your database suffers from index fragmentation when using UUID as the primary key, evaluate time-sortable alternatives, such as UUID v7, generated by another specific tool.
  • Store the UUID as your database's native type (like UUID in Postgres) when available, instead of in plain text, to save space and speed up searches.
  • Use capital letters only if the target system requires it; the RFC 4122 standard recommends lowercase letters.
  • Never use UUID as a substitute for authentication or access control: it identifies the resource, but does not prove who has permission to access it.

Perguntas frequentes

What is a UUID?

UUID stands for Universally Unique Identifier, a 36-character code in the format 8-4-4-4-12 separated by hyphens. It serves to give a unique name to records, files and keys in systems, without depending on a central server to avoid repetition. It is also called GUID on some platforms.

What is the difference between UUID and GUID?

In practice, none: they are two names for the same type of code. GUID is the most used term in the Microsoft ecosystem, while UUID is the name defined by RFC 4122, the international standard. The value generated here works in both cases.

What is UUID v4?

It is the version of UUID created from random numbers, the most used in day-to-day systems. This tool generates UUID v4 with the crypto.randomUUID() method, from the browser's Web Crypto API, which produces random values ​​with cryptographic quality.

Does this generator also create UUID v1 or v7?

No. This tool exclusively generates UUID v4 (random), the most commonly used version for API keys, sessions, and database records. If your system specifically requires v1 (based on time and network address) or v7 (random but time-orderable), you will need a tool made for those versions.

Can you generate UUID without a hyphen?

The generator delivers the code in standard format, with hyphens separating the groups 8-4-4-4-12. There is currently no ready-made on-screen option to remove hyphens; if your system requires the value without them, just apply a quick find and replace in your code editor.

How many UUID can I generate at once?

Up to 50 at a time. Just enter the desired quantity, click generate and use the "Copy all" button to take the entire list at once, with one UUID per line.

Can two UUIDs be the same?

It's extremely unlikely. A v4 UUID has 122 bits of entropy, which results in a large enough number of possible combinations that, in practice, each generated code can be treated as unique.

Is the generator free and safe?

Yes. Use is completely free and without registration, and the codes are created in the browser itself, without sending anything to external servers. You can generate as many UUIDs as you need and copy with one click.

Sobre este conteúdo

Escrito por:
Equipe Ferramenta Grátis

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UUID Generator v4 Online, Batch and Free