UUID Generator (v4, Bulk)

What the three checkboxes change

crypto.randomUUID returns a lowercase hyphenated version-4 UUID. Uppercase rewrites A–F as capitals and leaves the digits alone. Hyphens, on when you first open the page, keeps the 8-4-4-4-12 groups. Turning it off deletes the four hyphens and leaves 32 hex digits. Braces wraps that text in a single pair of curly braces. The switches combine: all three on produce a capital, hyphenated value inside braces. All three off, after you uncheck Hyphens, produce 32 lowercase hex digits with no wrapper.

The version nibble stays 4 because that is what randomUUID emits. This page does not build a version 1, 6, or 7 layout, and it does not accept an existing id to reformat. The lines you see were drawn on the last press of Generate UUIDs. If you check Uppercase and copy before you press Generate UUIDs again, the copy is still the previous casing. The note under the controls appears only when the requested count and the used count differ.

Quantity, Generate UUIDs, and the saved batch

Quantity starts at 5, and the list starts empty until the first Generate UUIDs. The used count is a whole number from 1 to 1,000. A non-number becomes 1. A fraction is rounded down. 1001 becomes 1,000, and the note reads Quantity must be a whole number from 1 to 1,000. Using 1,000. The same sentence appears for 0 or for a blank that collapsed to 1, with the used count filled in. Each line is an independent draw. Nothing in the batch is derived from the line above it.

This page writes Quantity, the three checkboxes, and the lines into local storage in this browser. A later visit restores them after the page hydrates, so a reload does not draw a new batch and does not forget a brace setting you turned on. There is no Clear button. Removing the site's stored data for this browser drops that record. Copy output and Download output read the lines on screen, one id per line, including braces when they were part of the draw.

When a random UUID is the id you want

Use version 4 when the other system already stores UUIDs and the id should not carry a creation time. The values do not sort by when you clicked. Two batches drawn a minute apart interleave in a text sort. That is the point of the random layout. If new rows should follow the clock, draw version 7 instead. The UUID v7 generator stamps a millisecond prefix and can show that time again. It stops at 100 lines and always prints lowercase hyphens.

A value you already have, including one of these lines, can be checked on the UUID validator. It reports version 4 as random and accepts braces, a missing hyphen set, and a urn:uuid: prefix. A MongoDB document that should use the 12-byte default id belongs on the ObjectID generator, not here. A longer comparison of version 4, version 7, and ULID is in UUID v4 vs UUID v7 vs ULID.

Clamped counts, braces, and a reload

The field's max is 1000, and Generate UUIDs enforces that even if the field is edited past it. You do not get 1,001 lines. You get 1,000, plus the note. A request of 1 is one line, not a paragraph of ids. Braces are a text wrapper only. They are not a second UUID format, and they are not added or removed when you toggle the box. The next Generate UUIDs applies the wrapper to every new line, or to none of them.

Because the last batch is restored, a shared computer will show the previous ids until someone generates again or clears site data. Treat that list like any other id sitting in the browser. The ids are not passwords, and version 4 does not hide a timestamp because it does not contain one. If a line you copied still has hyphens after you unchecked Hyphens, the copy was taken from the old batch. Press Generate UUIDs, then copy.

Rules and limitations

Generate UUIDs draws 1 to 1,000 values from crypto.randomUUID. Counts outside that range, and non-integers, are clamped, and a note states the count used. Uppercase, Hyphens, and Braces apply on the next draw. Hyphens starts on.

The list is one id per line. Quantity, the three checkboxes, and the lines are restored from local storage in this browser. Changing a checkbox does not rewrite the current lines. Copy and download read the lines on screen.

Common problems

If a checkbox seemed to do nothing, the lines on screen are the previous draw. Press Generate UUIDs before you copy.

If a reload brought the old batch back, this page stored it locally. Generate again for new ids, or clear the browser's site data to drop the saved list.

Frequently asked questions

About this tool

Maintained by Toolbench. For large or deeply nested files, split the input into smaller batches and verify representative results before using them in an import or application. Report reproducible problems through Contact.