What is the difference between UUID v4 and UUID v7?

UUID v4 is fully random, offering strong uniqueness with no ordering. UUID v7 embeds a Unix millisecond timestamp in its leading bits, so identifiers are time-ordered while still random enough to avoid collisions. Use v4 for opaque keys and v7 when you want database-friendly, sortable primary keys.

Are these UUIDs safe to use as database primary keys?

Yes. Both versions are 128-bit identifiers with an extremely low collision probability. UUID v7 is especially recommended for primary keys because its time-ordered layout reduces index fragmentation and improves insert performance compared to random v4 values.

Is my data private when generating UUIDs here?

Absolutely. Every UUID is generated entirely in your browser using the built-in Web Crypto API. Nothing is sent to a server, logged, or stored. Close the tab and the generated values are gone.

How many UUIDs can I generate at once?

You can generate between 1 and 100 UUIDs per batch. Adjust the count field, choose your version and formatting options, then click Generate to produce the full list, which you can copy individually or all at once.

UUID Generator

Generate UUID v4 and v7 identifiers in bulk, with copy and formatting options.

Options

Version

Count (1–100)

UppercaseRemove hyphens

Generated UUIDs

Click Generate to create UUIDs.

How to Use

Create unique identifiers in seconds.

Choose a Version

Pick UUID v4 for fully random identifiers or UUID v7 for time-ordered, sortable ones.

Set Count & Format

Enter how many UUIDs you need, then toggle uppercase or hyphen-free output.

Generate & Copy

Click Generate, then copy a single value or the whole list with one click.

UUID Tips

Choose the right identifier for the job.

Use v7 for Database Keys

UUID v7 embeds a timestamp in its leading bits, so rows insert in roughly chronological order. This keeps B-tree indexes compact and speeds up inserts versus random v4.

Use v4 for Opaque Tokens

When you don't want any information leaked from the identifier, v4's full randomness makes it ideal for session tokens, API keys, and public-facing references.

Formatting Is Cosmetic

Uppercase and hyphen removal change appearance only. The same 128-bit value is preserved, so it stays compatible when normalized back to canonical form.

Collisions Are Negligible

With 122 bits of randomness, the odds of generating a duplicate UUID are astronomically low, making both versions safe for distributed systems.