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BEAD

UUID Generator

Generate UUID v4 (random) and v7 (time-ordered) identifiers, one or many at a time.

GeneratorsDeveloper

🔒 Generated with window.crypto in your browser. Nothing is transmitted.

v4 vs v7

  • v4— 122 bits of randomness. Use when you want an opaque, unguessable ID and don't care about ordering.
  • v7 — a 48-bit Unix-ms timestamp followed by 74 random bits. Sortable by time, which makes it a much friendlier primary key for databases that index on insertion order (Postgres btrees, SQLite indices) than v4.

Frequently asked

▸Should I use v4, v7, or something else?

v4 is random — best when you want unguessable IDs (auth tokens, ephemeral keys). v7 is time-ordered — best when IDs go into a database index, because inserts stay sequential. v1 is timestamp + MAC and is mostly legacy.

▸Are these really unique?

Practically, yes. v4 has 122 bits of entropy — you'd need to generate billions per second for thousands of years before a collision became likely. v7 is even safer because the timestamp prefix segments the space.

▸Can I get the same UUID twice on purpose?

Yes — that's exactly what UUID v5/v3 are for (deterministic from a namespace + name). BEAD has a dedicated UUID v3/v5 tool for that.

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