Are these UUIDs RFC 4122 compliant?

Yes. Version and variant bits match RFC 4122 (version 3, variant 1).

UUID v3 uses MD5 over namespace bytes + name bytes. It is deterministic but not intended for cryptographic security.

Does any data leave my device?

No. Everything runs locally in your browser.

Can I use a custom namespace?

Yes. Provide any valid UUID as the namespace. Built-in options include DNS, URL, OID, and X.500.

UUID v3 Generator (RFC 4122, Name-Based)

Create deterministic UUID v3 identifiers from a namespace and name. Private by design—nothing leaves your device.

Controls

Namespace

Name (string) Encoded as UTF-8 per RFC 4122.

Batch names

Output format

Prefix (optional)

Suffix (optional)

Colorize example view (legend below) Show hyphenated in preview

Output

Tip: Press Ctrl/Cmd + Enter to regenerate with the same settings.

Legend (hyphenated view):
XXXXXXXX = time_low
XXXX = time_mid
3XXX = time_hi_and_version (version = 3)
XX XX = clock_seq (variant in high bits)
XXXXXXXXXXXX = node

Understanding UUID v3

UUID v3 is a deterministic, name-based identifier defined in RFC 4122. Instead of random numbers or timestamps, it hashes a namespace UUID together with a name using MD5, and then sets the proper version (3) and variant bits. The same namespace + name pair will always produce the same 128-bit UUID, which makes v3 ideal for stable keys derived from human-readable strings.

How it works

The algorithm concatenates the 16 bytes of the namespace UUID with the UTF-8 bytes of the name, runs MD5 over that byte sequence, and formats the 16-byte digest as a UUID: xxxxxxxx-xxxx-3xxx-yxxx-xxxxxxxxxxxx. The high nibble of the time_hi_and_version field is set to 3, and the RFC 4122 variant bits (10xx) are applied in clock_seq_hi_and_reserved.

Namespaces

Common built-ins are DNS (6ba7b810-9dad-11d1-80b4-00c04fd430c8), URL (6ba7b811-9dad-11d1-80b4-00c04fd430c8), OID (6ba7b812-9dad-11d1-80b4-00c04fd430c8), and X.500 DN (6ba7b814-9dad-11d1-80b4-00c04fd430c8). You can also supply any custom namespace UUID to project your own identifier space.

When to use v1 vs v3 vs v5 vs v4

v1 (time-based): Sorts by time; lightweight and widely compatible; uses clock sequence and node.
v3: Deterministic, MD5-based; great for “same input → same ID” scenarios (e.g., usernames, hostnames).
v5: Like v3 but uses SHA-1; often preferred in modern systems that want a stronger hash than MD5.
v4: Random; best when you want unpredictability and no dependence on names or time.

Note: MD5 is not suitable for cryptographic signatures, but it is specified for UUID v3 and is fine for stable identifiers.