DNS Namespace
Use when the input name is a domain, host, or DNS label such as example.com.
6ba7b810-9dad-11d1-80b4-00c04fd430c8
Free · Client-side · RFC 4122 · Name-Based
UUID v3 Generator
Generate deterministic UUID v3 values from a namespace UUID and a name string. Same input, same output — every time.
Part of WebEasier's UUID Generator suite for building topical authority around every UUID version and workflow.
UUID v3 Generator
Deterministic MD5 hash · Namespace + Name ·v=3
Great for stable identifiers derived from DNS names, URLs, OIDs, X.500 distinguished names, or your own custom namespace UUID.
How UUID v3 works: this tool combines the selected namespace UUID with each input name, hashes the bytes with MD5, then sets the UUID version nibble to 3 and the variant bits to the RFC 4122 standard.
DNS
URL
OID
X.500
Same namespace + same name = same UUID
Your UUID v3 results will appear here.
Choose a namespace, enter one or more names, then click Generate UUID v3.
What is a UUID v3?
A UUID v3 is a name-based UUID defined by RFC 4122. It is generated by hashing a namespace UUID and a name string with MD5, then formatting the result into the standard UUID layout. Because the process is deterministic, the same inputs always produce the same UUID.
9073926b-929f-31c2-abc9-fad77ae3e8eb
Version Bit
13th char = '3'
xxxxxxxx-xxxx-3xxx-yxxx-…
Hashing
MD5
Namespace bytes + name bytes
Behavior
Deterministic
Same inputs always match
Best For
Stable IDs
Records derived from known names
Overview
What is a UUID v3?
UUID version 3 is the classic name-based UUID format from RFC 4122. Instead of using random bits like UUID v4 or time fields like UUID v1, it derives the identifier from a namespace and a name string.
That makes UUID v3 ideal when you need a repeatable identifier for the same real-world input. For example, the same DNS name in the same namespace always maps to the same UUID v3.
UUID v3 is still widely used for compatibility, deterministic mapping, and stable foreign keys. For newer deterministic systems, many teams also consider UUID v5, which uses SHA-1 instead of MD5.
If you need random IDs instead, use our UUID v4 Generator. If you need sortable timestamps, use our UUID v1 Generator.
UUID v3 Format
9073926b-929f-31c2-abc9-fad77ae3e8eb
9073926b
hash bits
32 bits
32 bits
929f
hash bits
16 bits
16 bits
31c2
hash + v=3
16 bits
16 bits
abc9
variant bits
16 bits
16 bits
fad77ae3e8eb
remaining hash
48 bits
48 bits
The 13th character is always 3 for version 3.
The 17th character contains the RFC 4122 variant bits.
Security Note
UUID v3 is deterministic and uses MD5, so it should not be used for secrets, access tokens, passwords, or any security-sensitive values. It is best for stable naming and compatibility use cases.
Namespaces
Standard UUID v3 Namespaces
RFC 4122 defines four common namespace UUIDs for deterministic name-based generation.
URL Namespace
Use for full URLs such as https://webeasier.com/tools/.
6ba7b811-9dad-11d1-80b4-00c04fd430c8
OID Namespace
Use for ASN.1 object identifiers such as 1.3.6.1.4.1.
6ba7b812-9dad-11d1-80b4-00c04fd430c8
X.500 Namespace
Use for X.500 distinguished names such as CN=John Doe,OU=Users,O=Example.
6ba7b814-9dad-11d1-80b4-00c04fd430c8
How to choose the right namespace
- Choose DNS when the name is a hostname or domain.
- Choose URL when the full URL path matters.
- Choose OID for object identifiers in standards-heavy systems.
- Choose X.500 for directory or certificate naming.
- Use a custom namespace UUID when your application needs an isolated deterministic ID space.
Live Examples
Example UUID v3 Values
Fresh deterministic examples generated client-side on page load. Click any UUID to copy it.
How It Works
How UUID v3 Generation Works
UUID v3 generation follows a simple deterministic process. The namespace UUID is first converted to 16 raw bytes. The input name is UTF-8 encoded. Those bytes are concatenated and hashed with MD5.
- Normalize the selected namespace UUID into 16 bytes
- Encode the name string as UTF-8 bytes
- Concatenate namespace bytes + name bytes
- Hash the combined byte stream with MD5
- Set the version nibble to
0011(version 3) - Set the variant bits to the RFC 4122 standard
10 - Format the result as
xxxxxxxx-xxxx-3xxx-yxxx-xxxxxxxxxxxx
Because the same byte sequence always hashes the same way, UUID v3 is perfectly repeatable for the same namespace/name pair.
When to Use UUID v3
UUID v3 works best when you need stable identifiers derived from names:
Deterministic database keys
Domain name mapping
Stable URL identifiers
Integration key mapping
Directory object IDs
Idempotent import pipelines
Catalog deduplication
Namespace-scoped records
Legacy compatibility systems
Comparison
UUID v3 vs UUID v4 vs UUID v5
Choose the right UUID version for deterministic naming, random IDs, or stronger hashing.
| Version | Generation Method | Deterministic? | Best For | Notes |
|---|---|---|---|---|
| v3 | MD5(namespace + name) | Yes | Stable name-based IDs | Great for legacy compatibility and deterministic mapping |
| v4 | Cryptographically random | No | General-purpose unique IDs | Use our UUID v4 Generator |
| v5 | SHA-1(namespace + name) | Yes | Modern deterministic IDs | Preferred over v3 for many new name-based systems |
| v1 | Timestamp + node | No | Time-ordered records | Use our UUID v1 Generator |
| v7 | Unix ms timestamp + random | No | Modern sortable database IDs | Best fit for many new time-ordered applications |
If you want the same UUID from the same string input, choose UUID v3 or UUID v5. If you want a new random value every time, use UUID v4. If you want sortable timestamps, use UUID v1 or UUID v7.
FAQ
Frequently Asked Questions
Everything you need to know about UUID v3, namespaces, and deterministic identifiers.
A UUID v3 is a deterministic, name-based UUID format defined by RFC 4122. It takes a namespace UUID and a name string, hashes them with MD5, and formats the result as a standard UUID. The 13th character is always '3'.
Yes. The same namespace UUID and the exact same name string always generate the same UUID v3. That makes v3 useful for idempotent imports, stable entity mapping, and reproducible IDs.
RFC 4122 defines four built-in namespaces: DNS, URL, OID, and X.500. Each uses a fixed namespace UUID. This tool supports all four plus any custom namespace UUID you provide.
Both are deterministic, name-based UUID formats. The difference is the hash algorithm: UUID v3 uses MD5, while UUID v5 uses SHA-1. UUID v5 is often preferred for new projects, but UUID v3 remains valuable when you need compatibility with older systems or existing v3-based identifiers.
No. UUID v3 is deterministic and uses MD5. It should never be used for secrets, tokens, passwords, or anything that must be unpredictable. Use UUID v4 or a secure token generator for that.
Yes. Enter one name per line in the input box. The tool will generate a UUID v3 for each line using the selected namespace. This is useful for batch imports, deterministic mapping, and catalog normalization.
Choose UUID v3 if you specifically need MD5-based compatibility or must match older systems that already rely on UUID v3. For many new deterministic use cases, UUID v5 is the better default. For random IDs, use UUID v4. For sortable IDs, use UUID v7 or UUID v1 depending on your requirements.
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