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Glossary Data & Encoding

UUID

A UUID (universally unique identifier) is a 128-bit value, written as 36 characters such as 123e4567-e89b-12d3-a456-426614174000, that is unique for practical purposes without a central registry.

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In more detail

Version 4 UUIDs are random (122 random bits), so two systems can create identifiers independently with a negligible chance of clashing. Newer version 7 UUIDs start with a timestamp so they sort by creation time, which helps database indexes. They are not secrets and should not be used as passwords or tokens.

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UUID Generator

Generate cryptographically random RFC 4122 v4 UUIDs online, one at a time or in bulk.

See also

  • Glossary Hexadecimal
    Hexadecimal (hex) is the base-16 number system, using digits 0-9 and letters A-F, widely used as a compact way to write binary data.
  • Glossary Entropy
    In security, entropy measures how unpredictable something is, such as a password or key, usually expressed in bits.
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