A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across both space and time, with minimal coordination between parties generating them. UUIDs are represented as 32 hexadecimal digits, displayed in five groups separated by hyphens.

Why should I use UUIDs?

UUIDs are useful for generating unique identifiers without a centralized authority. They help avoid duplicate IDs in distributed systems, are suitable for database primary keys, and allow ID generation client-side without server communication.

What are the different UUID versions?

The main UUID versions are: UUID v1 (time-based), UUID v4 (random), UUID v5 (name-based with SHA1), and the newer UUID v7 (time-ordered). Each serves different purposes depending on your requirements.

How do I generate a UUID v7?

Select the "v7" tab in the generator above and click generate. UUID v7 is a time-ordered identifier defined in RFC 9562 that embeds a Unix millisecond timestamp in its most significant bits, making it sortable and ideal for database primary keys.

What is the difference between UUID and GUID?

UUID and GUID are functionally identical 128-bit identifiers. UUID (Universally Unique Identifier) is the term used in the IETF standards, while GUID (Globally Unique Identifier) is Microsoft's name for the same concept used across Windows and .NET.

Are UUIDs guaranteed to be unique?

UUIDs are practically unique rather than mathematically guaranteed. For two independent UUID v4 values the probability of a match is 1 in 2^122. Across a collection, collision probability grows with the number of pairs; use the collision calculator to estimate it.

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier encoded as a 26-character Crockford base32 string. Like UUID v7 it is time-ordered, so ULIDs sort chronologically while remaining URL-safe and compact.

Is this UUID generator free and private?

Yes. FastUUID is completely free and runs 100% in your browser. No UUID you generate is ever sent to a server, so the tool works offline and keeps your identifiers private.

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Random UUID with 122 random bits from a cryptographically secure source. A general-purpose identifier, not an access token.

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