UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems. UUIDs are standardized by RFC 9562 and are designed to be globally unique without requiring a central registry. They are commonly formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12.

UUID and GUID (Globally Unique Identifier) are essentially the same thing. "GUID" is the term commonly used in Microsoft/.NET ecosystems, while "UUID" is the standard term used in the RFC specification and most other platforms. The format and generation algorithms are identical.

For most use cases, use UUID v4 (random) for general-purpose unique identifiers, or UUID v7 (time-ordered) when you need sortable IDs, especially for database primary keys. Use v3 or v5 when you need deterministic UUIDs derived from a name and namespace. Avoid v1 if you need to hide timing information.

UUID v4 uses 122 bits of cryptographically secure random data (6 bits are reserved for version and variant). When generated with crypto.randomUUID() or crypto.getRandomValues(), the probability of collision is astronomically low — you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of a single collision.

UUID v7 embeds a Unix timestamp (milliseconds) in the first 48 bits, making the IDs naturally sortable by creation time. This is a major advantage for database indexes, especially B-trees, because new records are always appended rather than inserted randomly. This reduces page splits, improves write throughput, and makes range queries on time efficient.

UUIDs are designed to be unique in practice, but collisions are theoretically possible for random versions (v4, v7). The probability is vanishingly small when using a cryptographic random source. For deterministic versions (v3, v5), the same namespace + name will always produce the same UUID, which is by design.

Yes. Modern browsers provide crypto.randomUUID() and crypto.getRandomValues(), which use the operating system's cryptographic random number generator. Browser-generated UUIDs are equally secure to those generated server-side, with the added benefit that the values never leave your device.

Yes, UUIDs are commonly used as primary keys in databases. UUID v7 is recommended for this purpose because its time-ordered nature is friendly to B-tree indexes. If using v4, be aware that random insertion can cause index fragmentation in large tables. Most databases have a native UUID column type that stores the value efficiently as 16 bytes.

Different systems expect different formats. The canonical form uses hyphens (8-4-4-4-12). Microsoft/.NET often wraps UUIDs in braces: {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}. Some databases and APIs accept the 32-character hex string without hyphens. Use the format toggles above to match your target system's convention.

You can generate up to 1,000 UUIDs in a single batch using bulk mode. All generation happens client-side in your browser, so there is no server-imposed limit. For larger batches, simply generate multiple times and export the results.