UUID v3 Generator - Create Name-Based UUIDs with MD5

Generate namespace-based UUID version 3 online. Create consistent UUIDs using MD5 hashing for namespace and name combinations.

Namespace SettingsSHA-1

Version v3 and v5 UUIDs require a namespace and name to generate deterministic UUIDs.

✓
Must be a valid UUID. Use the dropdown to select a predefined namespace.
Any text string that will be hashed to create the UUID.

Try these examples:

What is UUID v3?

UUID version 3 is a namespace-based 128-bit identifier (36-char string) from RFC 4122 that uses MD5 hashing. It consists of:

  • Namespace UUID: A predefined or custom UUID namespace
  • Name: A user-provided string that gets hashed
  • MD5 hash: Applied to the namespace + name combination

Format example: 9125a8dc-52ee-365b-a5aa-81b0b3681cf6

How UUID v3 works

  1. Select a namespace UUID (predefined or custom)
  2. Concatenate the namespace UUID bytes with the name string bytes
  3. Calculate MD5 hash of the concatenated value
  4. Set version bits to 0011 (version 3)
  5. Set variant bits to 10 (RFC 4122 standard)
  6. Assemble as 32 hex digits with hyphens: 8-4-4-4-12 format

Advantages & Considerations

AdvantagesConsiderations
  • Deterministic generation
  • Same input = same UUID
  • No state required
  • No privacy concerns
  • MD5 is cryptographically weak
  • Not time-ordered/sortable
  • UUID v5 (SHA-1) preferred
  • No embedded creation time

UUID v3 Structure

BitsContent
0-47First 48 bits of MD5 hash
48-51Version (0011 for v3)
52-63Next 12 bits of MD5 hash
64-65Variant (10 for RFC4122)
66-127Remaining 62 bits of MD5 hash

Predefined Namespaces

NameUUIDPurpose
DNS6ba7b810-9dad-11d1-80b4-00c04fd430c8Domain names
URL6ba7b811-9dad-11d1-80b4-00c04fd430c8URLs
OID6ba7b812-9dad-11d1-80b4-00c04fd430c8ISO OIDs
X.500 DN6ba7b814-9dad-11d1-80b4-00c04fd430c8X.500 Distinguished Names

UUID v3 vs. other versions

VersionBased onUse casePrivacy
UUID v1Time + MACTime-ordered IDs⚠️ Reveals MAC
UUID v3Namespace + MD5Deterministic IDs✅ Private
UUID v4RandomSecure random IDs✅ Private
UUID v5Namespace + SHA-1Deterministic IDs✅ Private
UUID v6Time (reordered)Sortable IDs⚠️ Reveals MAC
UUID v7Time + randomSortable IDs✅ Private

Common Use Cases

  • URL-based identifiers: Creating UUIDs from URLs
  • Domain-specific IDs: Converting DNS names to UUIDs
  • Deterministic file IDs: Content addressing
  • User IDs: From email or username
  • Configuration entries: For consistent keys
  • Document references: Content management systems

Frequently Asked Questions

Is UUID v3 cryptographically secure?

Not really. UUID v3 uses MD5, which has known cryptographic weaknesses. For higher security, consider UUID v5 (SHA-1) or UUID v4 (random).

Will the same inputs always produce the same UUID v3?

Yes. UUID v3 is deterministic - the same namespace and name will always produce the identical UUID, making it useful for reproducible IDs.

What's the difference between UUID v3 and v5?

They work identically except v3 uses MD5 while v5 uses SHA-1. UUID v5 is generally preferred as SHA-1 is cryptographically stronger than MD5.

Can I create my own namespaces?

Yes. While RFC 4122 defines standard namespaces (DNS, URL, OID, X.500), you can create custom namespaces using any valid UUID.

Is UUID v3 suitable for security tokens?

No. Due to MD5's weaknesses and the deterministic nature, UUID v3 is not recommended for security tokens or anything requiring unpredictability.

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