Guide
About this uuid generator
This generator creates Universally Unique IDentifiers across every version defined in RFC 9562: nil, v1, v2, v3, v4, v5, v6, v7, and v8. Time-based, name-based, random, and sortable variants are all supported, with optional namespace and name inputs for v3/v5 and local domain for v2. Generation uses the browser’s Web Crypto API and runs entirely in the current tab.
How to use the uuid generator
- 1.Pick a version from nil through v8.
- 2.For v3 and v5, select a namespace and provide a name — the same inputs always produce the same UUID.
- 3.For v2, optionally enter a local identifier and domain.
- 4.Choose how many to generate (1–50) and click Generate UUIDs.
- 5.Copy any individual UUID, or use Copy All UUIDs to copy the whole list.
Important details
Which version should I use?
v4 (fully random) is the safest default for general identifiers. v7 (Unix-epoch milliseconds + random) sorts lexically and is ideal for database indexes when you want time-ordered rows. v5 (SHA-1 name+namespace) and v3 (MD5 name+namespace) produce deterministic UUIDs for the same inputs — useful for content-addressed or idempotent flows.
Version 6 versus version 1
Both v1 and v6 embed a Gregorian timestamp, but v6 reorders the timestamp so that lexical sort matches chronological order. This makes v6 friendlier than v1 for sorted indexes.
Uniqueness and storage
Random UUID collisions are extraordinarily unlikely, but a database should still enforce a unique constraint when uniqueness is a correctness requirement. Store UUIDs in a native UUID or compact binary type when your database supports one.
Frequently asked questions
Are these sequential UUIDs?
Only v1, v6, and v7 are time-based and therefore sortable. v4 is fully random and not sequential. v2, v3, v5, and v8 derive their bits from other inputs (local id, name+namespace hash, or vendor-specific data) and are not sortable by generation time.
Are UUIDs suitable for passwords or API keys?
Use a purpose-built secret generator for credentials. UUIDs are identifiers and should not automatically be treated as authentication secrets.
References: RFC 9562: Universally Unique IDentifiers