free tool — 100% browser, zero server
uuid generator
Generate UUID v4, v7, v1, nil, and max identifiers. No install, no account, nothing sent to any server.
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bulk generate
max 100 · same version as selected above
UUID versions explained
v4 — random
122 bits of CSPRNG randomness. No structure beyond version and variant bits. Best for most use cases — session IDs, API keys, database rows.
v7 — time-ordered
48-bit ms-precision Unix timestamp + 74 bits random. RFC 9562 (2024). Better for database primary keys — sequential inserts avoid B-tree page splits.
v1 — timestamp+MAC
100-ns time + clock sequence + node ID (random here). Time fields are interleaved across the UUID structure. Superseded by v7 for new projects.
nil & max
Nil is all zeros. Max is all ones (ffffffff-…). Both are RFC 9562 sentinels — useful as default/placeholder or range boundary values.
FAQ
What is UUID v4?
UUID v4 is a universally unique identifier generated from 122 bits of cryptographic randomness. It is the most widely used UUID version and is suitable for database primary keys, session tokens, and any scenario where a unique ID is needed without coordination between systems.
What is UUID v7 and how is it different from v4?
UUID v7 (RFC 9562, 2024) embeds a millisecond-precision Unix timestamp in the first 48 bits, making the IDs sortable by creation time. This is better for database indexes because time-ordered inserts avoid random page splits. v4 is fully random; v7 trades some randomness for sortability.
Is this UUID generator cryptographically secure?
Yes. v4 uses
crypto.randomUUID() or crypto.getRandomValues() — the same CSPRNG that browsers use for TLS. v7 uses crypto.getRandomValues() for the random bits and Date.now() for the timestamp. Neither v4 nor v7 can be predicted by an attacker.Can I use UUIDs generated here in production?
Yes. The generator runs entirely in your browser; nothing is sent to any server. The UUIDs are as random and unique as those generated by the
uuid npm package or Python’s uuid.uuid4().What is the collision probability of UUID v4?
Generating 1 billion v4 UUIDs per second for 85 years would give you about a 50% chance of a single collision. For any practical application, the collision probability is negligible.