Working with databases, APIs, or distributed systems often involves dealing with UUIDs. A single misplaced character can break your code. Our free Online UUID Validator provides a quick and easy way to check if a string is a valid, correctly formatted Universally Unique Identifier.

How to Use Our UUID Validator

Validating your UUID is an instant, automatic process:

1. Type or paste the UUID string you want to check into the input box above.
2. The tool will immediately validate the string as you type.
3. The result box will show whether the UUID is Valid or Invalid. If it's a standard version 1-5 UUID, it will also display the version number.

Example UUIDs

• `d5c1b6a0-7b3e-4d4e-8e6f-7f9a8c1b0d2e` - A valid UUID.
• `hello-world-this-is-not-a-uuid` - An invalid string that will fail validation.
• `d5c1b6a07b3e4d4e8e6f7f9a8c1b0d2e` - Invalid because it is missing the required hyphens.

What is a UUID?

A UUID (Universally Unique Identifier), sometimes also called a GUID (Globally Unique Identifier), is a 128-bit number used to uniquely identify information in computer systems. A standard UUID is represented as a 32-digit hexadecimal string split into five groups separated by hyphens, in the format `8-4-4-4-12`. For example: `f81d4fae-7dec-11d0-a765-00a0c91e6bf6`.

The key feature of UUIDs is that they are designed to be globally unique. This means that if you generate a UUID today, the probability of someone else, anywhere in the world, generating the exact same one is practically zero. This makes them extremely useful in distributed systems where multiple computers need to create unique IDs without coordinating with a central server.

What Are UUID Versions?

Not all UUIDs are created equal. There are several versions, each generated differently:

• Version 1: Generated from a timestamp and the MAC address of the computer that created it.
• Version 2: Similar to Version 1 but includes POSIX UID/GID information. It is rarely used.
• Version 3: Generated by hashing a namespace and a name using the MD5 algorithm.
• Version 4: The most common type. It is generated using purely random or pseudo-random numbers.
• Version 5: Generated by hashing a namespace and a name using the SHA-1 algorithm.

Our validator checks for the standard `8-4-4-4-12` format and can identify the version for any UUID from v1 to v5 based on the 13th character of the string.

Frequently Asked Questions (FAQ)

Q1: What's the difference between a UUID and a GUID?

For all practical purposes, the terms UUID and GUID can be used interchangeably. "UUID" is the term specified by the official standards, while "GUID" is the name Microsoft uses in its implementation. They both refer to the same 128-bit identifier format.

Q2: Does case matter in a UUID?

Officially, UUIDs are case-insensitive. The hexadecimal characters `A-F` can be either uppercase or lowercase. For example, `f81d4fae-...` is identical to `F81D4FAE-...`. Our validator correctly handles both cases.

Q3: What is a "Nil" UUID?

A "Nil" UUID is a special UUID composed entirely of zeros: `00000000-0000-0000-0000-000000000000`. It is used as a placeholder or to indicate a null or non-existent value. Our tool will recognize this as a valid UUID format.