UUID generator
Generates UUIDs of versions v1, v4 and v7. Single or batch — 5, 10, 25 or 50 at once. Export to clipboard or .txt.
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Generator settings
Version
Count
Case
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Result
Click 'Generate' — UUIDs will appear here.
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What is a UUID and which version to pick
UUID (Universally Unique Identifier) is a standardised 128-bit identifier that is, for practical purposes, unique in any context without central coordination. Defined in RFC 4122 and its update RFC 9562.
UUIDs are everywhere: database primary keys, session IDs, temporary file names, transaction IDs in distributed systems. The main advantage — two independent servers can generate UUIDs simultaneously with virtually zero collision risk.
UUID v4
Most popular550e8400-e29b-41d4-a716-446655440000
Fully random: 122 random bits. The third character of the third group is always 4 (version), first character of the fourth group is 8/9/a/b (RFC 4122 variant). Default in most libraries and databases. Has no order — cannot be sorted by creation time.
UUID v7
RFC 9562 · New018f4e6a-3c2b-7ce1-8f90-123456789abc
First 48 bits are Unix time in milliseconds. This makes v7 monotonically increasing — safe as a database primary key without index degradation (unlike v4). Standardised in RFC 9562 (2024). Recommended for new projects instead of v4 when sortability matters.
UUID v1
Legacyd9428888-122b-11e1-b85c-61cd3cbb3210
Contains a 100-ns timestamp and MAC address of the network interface. Unique, but exposes the machine's MAC and the exact generation time. Prefer v7 in new projects — it's also monotonic but without leaking network data.
UUID vs ULID vs NanoID
AlternativesUUID: 36 · ULID: 26 · NanoID: 21
UUID — the universal standard, supported everywhere, 36 chars with dashes. ULID — 26 base32 chars, monotonic, URL-safe but not an RFC. NanoID — compact, configurable alphabet and length, no time component. For URL slugs — NanoID; for DBs — UUID v7 or ULID; for APIs — UUID v4.