Generate RFC 4122-compliant UUIDs in bulk — version 1 (time-based), version 4 (random), or version 7 (sortable). All generation happens in your browser — nothing is sent to any server.
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft environments, is a 128-bit label used to uniquely identify information in computer systems. UUIDs are standardized by RFC 4122 and formatted as 32 hexadecimal digits split into five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
Because UUID collision probability is astronomically low — a v4 UUID has roughly 5.3 × 10²¹ possible values per bit of randomness — they can be generated independently on any number of machines without coordination, making them indispensable for distributed systems, databases, REST APIs, and client-side ID generation.
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crypto.randomUUID() in your browser
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
UUID v4 is the simplest choice and the most widely supported — it's purely random and has near-zero collision probability. However, because the values are random, inserting them into a B-tree index (like those used by PostgreSQL, MySQL, and most relational databases) causes frequent page splits and poor cache locality, which can degrade write performance at scale.
UUID v7 solves this by embedding a Unix millisecond timestamp in the most-significant bits, making IDs monotonically increasing within each millisecond. This preserves index locality — new rows land at the end of the index, just like an auto-increment integer — while still giving you the distributed generation and global uniqueness benefits of a UUID. If you're starting a new project and control your schema, v7 is generally the better choice for primary keys.