UUID v1 Generator - Create Timestamp-Based UUIDs Online

Generate timestamp-based UUID version 1 online. Create UUIDs that include the current time and MAC address for uniqueness.

Try these examples:

What is UUID v1?

UUID version 1 is a time-based 128-bit identifier (36-char string) from RFC 4122. It combines:

  • Timestamp: 60-bit value (100-nanosecond precision since 1582-10-15)
  • Clock sequence: 14-bit counter for clock adjustments
  • Node ID: 48-bit value (typically MAC address)

Format example: 2ed6657d-e927-11eb-9a03-0242ac130003

How UUID v1 works

  1. Calculate current timestamp (100ns intervals since 1582-10-15)
  2. Get/increment 14-bit clock sequence (for uniqueness if clock moves backward)
  3. Obtain 48-bit node ID (usually from MAC address)
  4. Set version bits (0001) and variant bits (10)
  5. Assemble as 32 hex digits with hyphens: 8-4-4-4-12 format

Advantages & Considerations

AdvantagesConsiderations
  • Time-ordered (sortable)
  • High performance generation
  • Distributed generation
  • Embedded creation time
  • MAC address privacy concerns
  • Clock synchronization issues
  • More predictable than random UUIDs
  • Not cryptographically secure

UUID v1 Structure

BitsContent
0-31Low 32 bits of timestamp
32-47Middle 16 bits of timestamp
48-59High 12 bits of timestamp
60-63Version (0001 for v1)
64-65Variant (10 for RFC4122)
66-79Clock sequence (14 bits)
80-127Node ID (48 bits)

UUID v1 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

  • Database keys: Distributed databases
  • Audit logs: Time-ordered tracking
  • Transaction IDs: Business processes
  • Session tracking: Web applications
  • Content addressing: CMS systems
  • IoT messages: Device communication

Frequently Asked Questions

Is UUID v1 cryptographically secure?

No. UUID v1 is predictable if timestamp and MAC address are known. For security, use random UUID v4 instead.

Can UUID v1 values collide?

Collisions are extremely unlikely in practice due to timestamp precision, clock sequence counters, and node identifiers.

Can I extract the creation time from a UUID v1?

Yes. The timestamp component can be extracted with appropriate algorithms available in most UUID libraries.

Are UUIDs v1 sortable by creation time?

Yes, but special sorting functions are needed. Direct string comparison won't work because time bits aren't sequential.

Does UUID v1 expose my MAC address?

By default, yes. Most implementations use the MAC address for the node ID. Privacy-focused implementations may use random node IDs instead.

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