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UUID Generator

Generate UUID v4 (random) and v7 (time-ordered) identifiers using the Web Crypto API. Nothing is stored or transmitted.

Frequently Asked Questions

What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems without coordination. The standard format is 8-4-4-4-12 hexadecimal characters separated by hyphens, e.g., 550e8400-e29b-41d4-a716-446655440000.
Are UUIDs truly unique?
For v4: with 122 random bits, the probability of collision after generating 1 billion UUIDs is about 1 in 10^18. In practice, you will never generate a duplicate. The randomness comes from the browser Web Crypto API.
Is my UUID logged anywhere?
No. UUIDs are generated locally with crypto.getRandomValues. There are no network requests and no storage.
Which UUID version should I use?
Version 4 (random) is the most popular choice for application-generated IDs since it requires no external input. Version 7 (time-ordered) is ideal for database primary keys because its time prefix means UUIDs sort chronologically, reducing B-tree fragmentation.
What is a nil UUID?
A nil UUID is all zeros: 00000000-0000-0000-0000-000000000000. It is used as a sentinel or placeholder value meaning "no UUID assigned".

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