This page focuses on random v4 unless otherwise labeled; newer versions add time ordering.

Astronomically unlikely for v4; still handle DB unique violations defensively.

UUIDs can join rows across tables—mind GDPR export/delete.

UUID Generator

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UUID generator: identifiers for APIs and databases

UUID v4 values provide distributed systems a low-collision identifier without a central allocator. They appear in REST responses, database keys, tracing IDs, and file names.

UUIDs are not secret—do not use them alone as auth tokens.

Practical tips

Store as CHAR(36) or binary(16) depending on DB best practices.
Batch-generate for fixtures but avoid predictable seeds.
Combine with ULID when sortable time ordering matters.
Log correlation IDs across microservices.

Common questions

v4 vs v7?: This page focuses on random v4 unless otherwise labeled; newer versions add time ordering.
Collisions?: Astronomically unlikely for v4; still handle DB unique violations defensively.
Privacy?: UUIDs can join rows across tables—mind GDPR export/delete.

Related tools on Toolfex

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