UUID / GUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by the Open Software Foundation. It is used to uniquely identify information in computer systems. The term GUID (Globally Unique Identifier) is a Microsoft implementation of the UUID standard and is used interchangeably.

UUID v1 generates time-based identifiers using the current timestamp and the host machine's MAC address (or a random node), making them chronologically sortable but potentially predictable. UUID v4 uses purely random numbers, offering 122 bits of entropy and is the most commonly used version. UUID v7 (RFC 9562) combines a Unix timestamp with random data, providing time-ordering like v1 but with the simplicity and security of random generation.

UUIDs are designed to be unique across space and time. UUID v4 has 2^122 possible values — the probability of collision is extremely low. UUID v1 uses timestamps and node identifiers to guarantee uniqueness within a system. UUID v7 combines timestamps with random bits, making collisions practically impossible under normal usage. All versions are safe for production use as database primary keys, distributed system identifiers, or API resource IDs.

UUID v7 is generally recommended for database primary keys because it is time-ordered, which improves B-tree index performance and reduces page splits in databases like PostgreSQL and MySQL. UUID v4 values are randomly distributed and can cause index fragmentation at scale. UUID v1 also provides time-ordering but may leak the timestamp and potentially the machine identity. For modern applications, UUID v7 offers the best balance of performance, privacy, and sortability.

Yes, this UUID generator is completely free to use. There are no usage limits, no registration required, and no premium tiers. All UUID generation happens locally in your browser using the Web Crypto API — no data is sent to any server. You can generate as many UUIDs as you need for personal projects, commercial applications, or any other use.

GUID stands for Globally Unique Identifier. It is Microsoft's implementation of the UUID standard. Conceptually and structurally, they are the same 128-bit identifiers, though Microsoft tools traditionally write them in uppercase and sometimes wrap them in curly braces.

The Web Crypto API uses cryptographically secure pseudorandom number generators (CSPRNG) provided by the host operating system (such as /dev/urandom on Unix systems). This is much more secure than Math.random(), preventing predictability in production systems.

For UUID v4, you would need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision. For UUID v7, because the first 48 bits represent a timestamp, collisions can only happen if two identical random parts are generated within the exact same millisecond, which is highly improbable.

UUID v7 stores a 48-bit Unix timestamp in its most significant bits (at the beginning of the string). Since values generated later will have a larger timestamp, they naturally sort lexicographically after earlier ones, matching creation order.

Yes. This generator lets you generate up to 500 UUIDs at a time. You can choose the format (standard, uppercase, no hyphens, CSV, JSON array) and copy or download them instantly.