Most UUID generators only give you random v4 IDs — different every time, even for the same logical entity. Sometimes you need the opposite: the same input always producing the same ID. That’s exactly what UUID v5 is for.
What Is the UUID v5 Generator?
The UUID v5 Generator hashes a namespace UUID and a name together using SHA-1, per RFC 4122, to produce a deterministic UUID — the same namespace and name will always generate the identical UUID, with no randomness involved.
How to Use It
- Open the tool at /tools/uuid5-generator.
- Choose one of the four standard RFC 4122 namespaces (DNS, URL, OID, X.500) or supply your own custom namespace UUID.
- Enter a name (a domain, URL, or any string you want a stable ID for).
- Copy the resulting UUID v5.
Key Features
- Fully RFC 4122-compliant, including correct version (5) and variant bit assignment.
- Standard predefined namespaces built in, plus support for a custom namespace UUID.
- Deterministic by design — verify it yourself by re-entering the same namespace/name pair and getting an identical result every time.
- Computed with the native Web Crypto SHA-1 API — nothing sent to a server.
When to Use This Tool
- Deriving a stable internal ID from an external identifier (like a URL or email address) without maintaining a separate lookup table.
- Generating reproducible test fixtures where IDs need to match across test runs.
- Building systems that need to detect duplicates by re-deriving the same ID from the same source data.
Try It Now
Open UUID v5 Generator directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Security & Validators collection on WebdevToolbox — free, browser-based developer tools with no login required.