Générateur UUID v7

Génération gratuite en ligne d'UUIDv7, et présentation des méthodes de génération d'UUIDv7 dans divers langages.

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What is a GUID?

A GUID (Globally Unique Identifier) is a globally unique identifier that can be generated through several different algorithms. The GUIDs on this site are generated using a secure random number generator.

UUID Format

UUIDs are 128-bit values typically represented as 32 hexadecimal digits displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and 4 hyphens). For example: 550e8400-e29b-41d4-a716-446655440000

What is a Version 1 UUID?

A Version 1 UUID is a universally unique identifier that is generated using a timestamp and the MAC address of the computer on which it was generated. This version includes:

  • 60-bit timestamp (number of 100-nanosecond intervals since October 15, 1582)
  • 12-bit clock sequence
  • 48-bit node identifier (usually the MAC address)

What is a Version 4 UUID?

A Version 4 UUID is a universally unique identifier that is generated using random numbers. The Version 4 UUIDs produced by this site were generated using a secure random number generator. This version includes:

  • 122 random bits
  • 6 bits for the version (set to 0100)
  • 2 bits for the variant (set to 10)

What is a Version 7 UUID?

A Version 7 UUID is a universally unique identifier that is generated using a timestamp, a counter and a cryptographically strong random number. Generally, Version 7 UUIDs have better entropy (i.e. randomness) than Version 1 UUIDs. This version includes:

  • 48-bit timestamp (milliseconds since Unix epoch)
  • 12-bit counter or random data
  • 62 bits of cryptographically secure random data
  • 4 bits for version (set to 0111)
  • 2 bits for variant (set to 10)

Version 7 UUIDs are particularly useful for database primary keys because they maintain time-ordering while providing good randomness.

What is a Nil/Empty UUID?

A Nil/Empty UUID is a special form that contains all zeros. It has the format: 00000000-0000-0000-0000-000000000000 and is often used to represent a null or undefined UUID.

UUID Versions Comparison

VersionGeneration MethodTime-orderedPrivacyUse Case
Version 1Timestamp + MAC addressYesLowDistributed systems where uniqueness is critical
Version 4RandomNoHighGeneral purpose, privacy-sensitive applications
Version 7Timestamp + RandomYesHighDatabase keys, sortable identifiers

Benefits of Different UUID Versions

  1. Version 1: Guarantees uniqueness across space and time, but reveals MAC address
  2. Version 4: High randomness and privacy, but no ordering
  3. Version 7: Combines benefits of time-ordering and randomness, suitable for databases

Common Use Cases

  • Database Primary Keys: UUIDs provide unique identifiers without requiring a centralized key generator
  • Distributed Systems: Ensure unique identifiers across multiple systems without coordination
  • URLs and Resource Identifiers: Create unguessable, unique identifiers for web resources
  • Session Identifiers: Secure session management in web applications
  • Transaction IDs: Track operations across distributed systems

Security Considerations

  • Version 1 Privacy: May expose MAC address, which can be a privacy concern
  • Version 4/7 Security: Use cryptographically secure random number generators to prevent predictability
  • Predictability: Predictable UUIDs can be a security risk in certain applications

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