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Create UUID version 4 values in the browser. The form opens at count 1, Standard format, and duplicates off. The list stays empty until you click Generate UUID. Standard output is 36 lowercase characters. Uppercase, braces, and no hyphens are the other three shapes, and they do not combine. This page does not make a version 7 UUID.
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Last updated: October 8, 2026 · Published: 2026-04-09 · Updated: 2026-10-08
Generates RFC 4122 style UUID v4 values for development, QA, and integration workflows.
Set options and click generate
It draws a version 4 UUID and then applies one format. crypto.randomUUID is used when the browser provides it. If that function is missing, the page fills 32 hex digits with Math.random, sets the version digit to 4, and sets the variant digit to 8, 9, a, or b. A value that does not match that layout is discarded before it is shown.
The note under the controls calls the result RFC 4122 style. The four buttons are Standard, Uppercase, With braces, and No hyphens. Picking a new button leaves the UUIDs already on screen in the old format until the next click.
Copy places one UUID on each line. If the clipboard API fails, the page copies through a hidden text field. The values stay in the browser.
Four steps. The list changes only when you click Generate.
The box accepts 1 through 100. A blank value becomes 1.
Standard is selected. Uppercase, braces, and no hyphens replace that shape. They do not stack.
The list stays empty until the click. Duplicates are off, so the click skips a formatted value it already drew.
Copy to clipboard puts one UUID on each line.
The form as it opens, and what one click does with those settings.
| Setting | This generator |
|---|---|
| Version | 4 only. Version digit is 4. Variant digit is 8, 9, a, or b |
| Source | crypto.randomUUID, or Math.random if that function is missing |
| Output | Empty until Generate UUID |
| Default count | 1, clamped to 1–100 |
| Default format | Standard, 36 lowercase characters |
| Duplicates | Off. Checked on the formatted text of this click |
| Attempt cap | Unique: the larger of 2,000 and 30 times the count |
| Format changes | Apply on the next click. The current list stays as drawn |
| Copy | One UUID per line. A hidden textarea is the fallback |
| Not produced | Version 1, 3, 5, 6, 7, or the all-zero UUID |
The format buttons choose the shape of the next click.
1 to 100, starting at 1. The button says Generate UUID at 1 and Generate UUIDs above that.
36 lowercase characters, hyphens in the 8-4-4-4-12 groups. The version digit is 4.
The same 36 characters in capitals. It does not also add braces or remove hyphens.
38 characters. The UUID stays lowercase inside one pair of curly braces.
32 hex characters. The 4 remains the 13th character.
Off by default. Uniqueness is checked on the formatted string for that click only.
The version-4 shape before formatting is eight, four, four, four, and twelve hex digits. The first digit of the third group is 4. The first digit of the fourth group is 8, 9, a, or b.
| Format | Characters | Shape |
|---|---|---|
| Standard | 36 | 8-4-4-4-12, lowercase, with hyphens |
| Uppercase | 36 | The same groups, in capitals |
| With braces | 38 | {lowercase uuid} |
| No hyphens | 32 | Hex only. The 13th character is 4 |
A click asks for the number in the box, then stops early if it runs out of attempts. With duplicates off, that ceiling is the larger of 2,000 and 30 times the count. With duplicates on, it is the larger of 250 and 5 times the count. The next click starts over. Nothing is saved between clicks.
Short definitions for the words on this page.
A 128-bit identifier whose version digit is 4 and whose variant digit is 8, 9, a, or b. The other bits are random.
36 lowercase characters with hyphens. This is the format selected when the page opens.
The first hex digit of the fourth group. On this page it is 8, 9, a, or b.
The browser function used when it exists. The Math.random layout is the fallback.
With duplicates off, the click skips a value whose formatted text was already kept in that same click.
Version 4 only, the four formats and their character counts, and why the list can stop short of the count.
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