RFC 9562 · SHA-1 · DETERMINISTIC

UUID v5 Generator

Generate deterministic UUID v5 identifiers from a namespace and name using SHA-1. Test reproducibility, inspect UTF-8 input bytes, compare RFC vectors and generate UUIDs in bulk directly in your browser.

Browser-only: Namespace and name values are processed locally.

1. Choose Namespace

Namespace scopes your names

Selected Namespace DNS

Namespace UUID 6ba7b810-9dad-11d1-80b4-00c04fd430c8

2. Enter Name

Exact bytes are hashed

Names: 0 Characters: 0 UTF-8 Bytes: 0

UUID Format

RFC v5 Test Vector DNS + www.example.com 2ed6657d-e927-568b-95e1-2665a8aea6a2

UUID v5 Results

Generated 0

Unique UUIDs 0

Duplicates 0

Deterministic Yes

Reproducibility Check

Can this UUID be recreated?

Namespace —

Name —

UTF-8 Bytes —

SHA-1 —

Why Exact Input Matters

UUID v5 hashes bytes, not meaning

Input A example.com

≠

Input B example.com/

These two names are different byte sequences. UUID v5 does not silently remove spaces, change letter case or normalize URLs. Establish a canonical naming rule before sharing UUIDs between systems.

What is UUID v5?

UUID v5 is a deterministic, name-based UUID format. Instead ofgenerating a random identifier, it combines a namespace UUID witha name and applies SHA-1 to the resulting byte sequence.

The first 128 bits of the SHA-1 digest are adapted into UUID formatby setting the version bits to 5 and the RFC variant bits.Because the process is deterministic, the same namespace and exactname always produce the same UUID.

UUID v5 Namespaces

DNS:Domain names such as example.com
URL:URLs and URL-like identifiers
OID:Object identifiers
X.500:Distinguished names
Custom:Application-controlled namespace UUIDs

When UUID v5 Is Useful

Stable IDs for URLs and domains
Deterministic data imports
Idempotent ETL operations
Cross-system record matching
Stable test fixtures
Namespaced cache or resource identifiers

UUID v5 vs UUID v4

UUID v4 is primarily random and is useful when a new unpredictableidentifier is required. UUID v5 is deterministic and is useful whenan identifier must be reproducible from known input.

UUID v5 vs UUID v3

UUID v3 and UUID v5 both use a namespace and name. UUID v3 uses MD5,while UUID v5 uses SHA-1. For new deterministic UUID implementations,UUID v5 is generally the preferred choice when interoperability withthe UUID v5 standard is required.

Frequently Asked Questions

UUID v5 is a deterministic, name-based UUID format. It combines a namespace UUID and a name string, hashes them using SHA-1 and converts the result into a UUID with version 5 and the RFC variant.

Yes. When the namespace UUID and name bytes are exactly the same, a compliant UUID v5 implementation produces the same UUID.

A namespace is a UUID that scopes the name being hashed. Standard namespaces include DNS, URL, OID and X.500. Applications can also use their own custom namespace UUID.

No. UUID v5 hashes the supplied name bytes. Differences such as uppercase letters, whitespace, URL trailing slashes or Unicode representations can produce different UUIDs.

No. UUID v5 is deterministic rather than random. The same namespace and name produce the same UUID.

No. UUID v5 is designed for deterministic identifiers, not passwords, authentication tokens, secrets or digital signatures.

Yes. Enter one name per line and the tool generates a deterministic UUID v5 for each name using the selected namespace.

Both are deterministic namespace-based UUIDs, but UUID v3 uses MD5 while UUID v5 uses SHA-1 for the UUID generation algorithm.

No. SHA-1 generation and UUID formatting are performed locally in your browser.