UUID Generator

MD5 name-based UUIDs

UUID v3 Generator

Generate deterministic UUID v3 values from a namespace and a name using MD5, for legacy systems that expect version 3 identifiers.

Deterministic name-based UUIDs

UUID v5 & v3 Generator

Namespace
Deterministic V3 UUID
9073926b-929f-31c2-abc9-fad77ae3e8eb

The same name and namespace always produce the same UUID. Computed locally in your browser.

Not sure? Use UUID v4 for random IDs, UUID v7 for sortable database IDs, and GUID for Microsoft/.NET systems.
Generated locally in your browser.No backend used.Nothing is uploaded.
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UUID v4 Random identifiers for APIs, files, sessions and records.

UUID v3 is a name-based UUID that hashes a namespace and a name using MD5. Like UUID v5, it is deterministic, so identical inputs always produce the same identifier. Most new projects should choose UUID v5 instead, but v3 remains useful for compatibility with systems that already use it.

Key takeaways

  • Deterministic name-based UUID, computed with MD5.
  • Behaves like UUID v5 but uses the older MD5 hash.
  • Prefer UUID v5 for new work; use v3 for existing v3 data.

When to use UUID v3

UUID v3 exists mainly for compatibility. If another system already generates v3 identifiers from a namespace and name, you need v3 to reproduce the same values. The algorithm is identical to UUID v5 except that it hashes with MD5 rather than SHA-1.

For brand-new systems that just need deterministic name-based UUIDs, UUID v5 is the better default because SHA-1 is a stronger hash function.

How UUID v3 is built

The generator concatenates the 16 bytes of the namespace UUID with the UTF-8 bytes of the name, hashes the result with MD5, keeps the first 16 bytes, then sets the version nibble to 3 and the RFC variant bits. The output is a standard UUID that any parser will accept.

bytes  = md5( namespaceBytes + utf8(name) )
uuid   = bytes[0..15] with version=3 and RFC variant

Namespaces work the same way

As with UUID v5, you can use the DNS, URL, OID or X.500 namespaces, or provide your own custom namespace UUID. The same namespace and name always produce the same v3 UUID.

FAQ

UUID v3 Generator questions

What is the difference between UUID v3 and v5?

Both are deterministic name-based UUIDs. UUID v3 hashes with MD5 and UUID v5 hashes with SHA-1. UUID v5 is generally recommended for new systems.

Is UUID v3 still valid?

Yes. UUID v3 is a valid, standardized version. It is mostly used for compatibility with existing v3 identifiers.

Can I recompute a UUID v3 later?

Yes. Given the same namespace and name, you can always recompute the identical UUID v3 value.

UUID v3 Generator - Name-Based MD5 UUIDs Online