What is the difference between UUID v4 and v7?

v4 is random, so identifiers are unpredictable but unordered. v7 puts a millisecond timestamp at the front, so IDs generated later sort after earlier ones — better for database primary keys and indexes.

Are these UUIDs safe to use as unique keys?

Yes. v4 uses the browser's cryptographically secure random generator, making collisions astronomically unlikely. They're suitable for database keys, request ids and file names.

Are the UUIDs generated on a server?

No. They're generated locally in your browser, so nothing is transmitted or logged.

Developer ToolsRuns in your browser

UUID Generator

Generate one or many UUIDs — cryptographically random v4 or time-ordered v7 — and copy them in a click.

Version

Quantity

1 UUIDs

What this does

Generate universally unique identifiers on demand. Version 4 UUIDs are fully random; version 7 UUIDs embed a timestamp so they sort chronologically, which is handy for database keys. Generate up to hundreds at once.

How to use it

1A fresh UUID appears as soon as the page loads.
2Choose the version (v4 or v7) and how many you want.
3Copy a single value or the whole list.

Examples

v4: 550e8400-e29b-41d4-a716-446655440000
v7 values sort in the order they were created

Frequently asked questions

What is the difference between UUID v4 and v7?: v4 is random, so identifiers are unpredictable but unordered. v7 puts a millisecond timestamp at the front, so IDs generated later sort after earlier ones — better for database primary keys and indexes.
Are these UUIDs safe to use as unique keys?: Yes. v4 uses the browser's cryptographically secure random generator, making collisions astronomically unlikely. They're suitable for database keys, request ids and file names.
Are the UUIDs generated on a server?: No. They're generated locally in your browser, so nothing is transmitted or logged.

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