What is the difference between v4 and v7?

Both are random. Version 7 embeds a timestamp in the first bits, so values created later sort later, which is what you want for a database primary key.

Which version should I use?

Use v7 for anything stored in a database, because sequential inserts avoid page splits. Use v4 when you specifically need unpredictable ordering.

Are they unique without a database?

Yes. With 122 random bits in v4, or 74 random bits plus a timestamp in v7, a collision is not a practical concern.

UUID Generator

Generate random UUID v4 or time-ordered UUID v7 values in bulk, with optional uppercase, brace, and no-dash formatting for your database. No server needed.

A UUID generator creates 128-bit identifiers. Version 4 values are random, while version 7 values start with a millisecond timestamp, which makes them sort in creation order and keeps indexes compact in a database.

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Questions about uuid generator

What is the difference between v4 and v7?: Both are random. Version 7 embeds a timestamp in the first bits, so values created later sort later, which is what you want for a database primary key.
Which version should I use?: Use v7 for anything stored in a database, because sequential inserts avoid page splits. Use v4 when you specifically need unpredictable ordering.
Are they unique without a database?: Yes. With 122 random bits in v4, or 74 random bits plus a timestamp in v7, a collision is not a practical concern.

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