Developer Tools
UUID Generator
Generate UUID v4 (random) or v7 (timestamp-ordered). Bulk mode supported, instant export to JSON, CSV, or SQL.
Fully random — opaque IDs
10 UUIDs generated
UUID v4 vs v7
UUID v4 is the classic random UUID — 122 bits of entropy, zero ordering. Perfect when you need an opaque identifier and don't want consumers to infer creation time.
UUID v7 (RFC 9562, 2024) puts a millisecond timestamp in the first 48 bits, then 74 bits of randomness. The result: lexicographic sort order matches creation order, which massively improves database index performance compared to v4.
Frequently Asked Questions
What is a UUID?▾
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify records across distributed systems without coordination. The same as Microsoft's GUID. Standard format: 8-4-4-4-12 hex digits, e.g. f47ac10b-58cc-4372-a567-0e02b2c3d479.
What's the difference between v4 and v7?▾
UUID v4 is fully random — great for IDs that should not leak time information. UUID v7 (newer, 2022) embeds a millisecond timestamp at the start, so IDs sort chronologically — much friendlier for database indexes and pagination.
Are these UUIDs cryptographically random?▾
Yes — we use crypto.getRandomValues() (the browser's cryptographic random source) for both v4 and v7. Collisions are statistically impossible at any reasonable scale.
Can I generate UUIDs in bulk?▾
Yes — set the count to anything from 1 to 1,000. We generate them all instantly. Click "Copy all" to grab the whole list, or use the format selector to get them as JSON, CSV, or SQL INSERT values.
When should I use v7 instead of v4?▾
Use v7 when IDs go into a sorted index (Postgres B-tree, MongoDB _id, etc.) — chronological order dramatically reduces index fragmentation and speeds up insert performance. Use v4 when you want zero information leakage about creation time.