Free Converter
UUID / GUID Generator
Generate UUID v4 (GUID) values instantly in your browser. Free, private, and client-side — no data sent to any server.
Generate UUID v4 (GUID) values instantly in your browser. Free, private, and client-side — no data sent to any server.
UUIDs (Universally Unique Identifiers, also called GUIDs in Microsoft contexts) are 128-bit identifiers that can be generated independently across systems with negligible collision probability. The standard form is 32 hex characters in 8-4-4-4-12 groups, separated by hyphens (550e8400-e29b-41d4-a716-446655440000). Multiple versions exist with different generation strategies; v4 (random) is the most common.
v4 UUIDs derive their uniqueness from 122 bits of randomness (six bits are fixed for version and variant). The collision probability is so small that for practical purposes UUIDs can be treated as globally unique without coordination — two systems generating UUIDs independently will not produce duplicates over any realistic timescale.
This generator produces v4 UUIDs in the standard hex-with-hyphens format. The randomness comes from the browser's cryptographically secure random number generator (window.crypto.getRandomValues), suitable for security-sensitive purposes. Bulk generation is supported for filling in test fixtures or seeding databases.
UUIDs let distributed systems generate identifiers without coordinating with a central database. Each service can produce IDs locally without round-trips to a counter, and the resulting IDs are guaranteed not to collide with IDs generated elsewhere. This enables scaled-out architectures where ID generation is not a bottleneck.
UUIDs also make IDs unguessable. Sequential numeric IDs leak information — total user count, account age, signup velocity. UUIDs reveal nothing. APIs that expose IDs to users benefit from UUIDs both for security and for forward-compatibility with sharded backends.
Click generate, get a v4 UUID.
UUIDs are 128 bits, displayed as 32 hexadecimal digits in five groups separated by hyphens. The grouping (8-4-4-4-12) is purely cosmetic; the value is a single 128-bit integer. v4 UUIDs encode 122 bits of randomness with the remaining 6 bits fixed: the version field (4 bits, value 4) identifies the variant.
Browser support: crypto.randomUUID() is available in modern browsers (Chrome 92+, Firefox 95+, Safari 15.4+) and produces v4 UUIDs directly. Older browsers fall back to manually combining 16 random bytes from crypto.getRandomValues with version/variant bits set correctly.
Collision probability: with 2^122 possible random UUIDs, the chance of generating two identical values is negligible. Even at 10^9 UUIDs generated, the probability of a single collision is around 10^-18 — about 10 trillion times less likely than picking an atom on Earth at random.