UUID v5 Generator
Deterministic: same namespace + name always produce the same UUID.
What is UUID v5 Generator
UUID v5 is a name-based identifier generated by hashing a namespace UUID and a name string together using SHA-1. The key property is determinism: given the same namespace and name, UUID v5 always produces the same output. This makes it ideal for generating stable, reproducible IDs from existing data without a central registry.
How to use
- Select a namespace from the dropdown (DNS, URL, OID, X.500, or a custom UUID).
- Type the name you want to hash (e.g. a domain, a username, or a resource path).
- The UUID v5 is generated automatically and updates as you type.
- Click Copy to copy the result to your clipboard.
Use cases
A developer needs stable IDs for imported user records identified by email. Using the DNS namespace and each email address as the name, UUID v5 produces the same UUID for 'alice@example.com' every time — so re-importing the same data never creates duplicate records.
Frequently asked questions
What does deterministic mean for UUID v5?
It means the same namespace + name combination always produces the exact same UUID, regardless of when or where you run the generator. This is guaranteed by the SHA-1 hash.
What is a namespace UUID?
A namespace UUID scopes the name so that 'example.com' in the DNS namespace produces a different UUID than 'example.com' in the URL namespace. The RFC 4122 defines DNS, URL, OID, and X.500 namespaces.
How is UUID v5 different from v3?
Both are name-based and deterministic, but v5 uses SHA-1 while v3 uses MD5. SHA-1 is stronger, so v5 is the recommended choice for new applications.
Is UUID v5 suitable as a primary key?
Yes, as long as your (namespace, name) pairs are stable and unique. It is especially useful for deduplicating imported records or mapping external identifiers to UUIDs.
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