🆔UUID Generator - Generate UUID v4 and v7 Online in Bulk

How to use UUID Generator

1. 1Choose a version: v4 if unsure; v7 for database primary keys or whenever IDs should sort by creation order
2. 2Drag the slider to choose how many (1 to 100); changing the count generates a fresh batch
3. 3Toggle uppercase, no hyphens or braces as needed; the options combine and the result updates instantly
4. 4Click Copy all for a one-per-line list, or Regenerate for a new batch

FAQ

Can the UUIDs collide?

Not in practice. A v4 UUID has 122 random bits, about 5.3 × 10³⁶ possible values. Even across a trillion UUIDs, the chance of a single duplicate is roughly 1 in 10 trillion; for a 50% chance you would need about 2.7 × 10¹⁸ of them, which at a billion per second takes 86 years. We generated 100,000 in the browser and found no duplicates. A v7 still carries over 70 random bits within each millisecond, so two computers generating at the same moment will not clash, and this tool also increments a counter for IDs made in the same millisecond; a test batch of 200,000 v7 UUIDs had no duplicates and was strictly increasing.

Should I use v4 or v7?

v4 is random apart from the version bits: universally supported and revealing nothing about when it was made. v7 puts the creation time (in milliseconds) in its first 48 bits and fills the rest with random data, so earlier UUIDs sort first. As a database primary key, new rows always land at the end of the index instead of scattered through it as with v4, so inserts are faster, the index stays compact, and sorting by key means sorting by creation time. The trade-off is that anyone can read the creation time from a v7, so use v4 where that should stay private, such as public share links. v7 only became a formal standard with RFC 9562 in 2024, so check that your database or library handles it.

How can I tell which version a UUID is?

The standard form has 36 characters: 32 hex digits in five hyphen-separated groups of 8-4-4-4-12, for example c168e339-f227-466b-bdb3-004f952c1e13. The first character of the third group is the version, 4 for v4 and 7 for v7, and the first character of the fourth group is always 8, 9, a or b. In a v7 the first 12 hex digits (ignoring hyphens) are the creation time in milliseconds: 01a1affe211e is 1793954029854 in decimal, which is 2026-11-06 08:33:49.854 UTC. We tested a batch of each version from this tool and every one had the correct format.

When should I use uppercase, no hyphens or braces?

Lowercase with hyphens is the standard form, and what most programming languages and PostgreSQL's uuid type print. Uppercase in braces is Microsoft's style: the Windows registry and Visual Studio .sln and project files write GUIDs as {C168E339-F227-466B-BDB3-004F952C1E13}. Without hyphens you get 32 characters, handy for file names, URL segments or a CHAR(32) column. The options can be combined.

What is the difference between a UUID and a GUID?

There is none. GUID is Microsoft's name for the same format; Windows just tends to write it in uppercase inside braces. Tick Uppercase and Wrap in braces to get a Windows-style GUID.

What column type should I store it in?

As text it takes 36 characters with hyphens or 32 without; as binary it is 16 bytes. PostgreSQL has a native uuid type (16 bytes), SQL Server uses uniqueidentifier, and MySQL commonly uses CHAR(36), or BINARY(16) to save space, with MySQL 8's UUID_TO_BIN and BIN_TO_UUID functions converting between the two.

Are they generated locally, and are they secure?

Yes. Your browser generates them with a cryptographically secure RNG, with no network request and no logging, so we never see them. v4 uses crypto.randomUUID where available (Chrome 92, Firefox 95, Safari 15.4 and later) and falls back to crypto.getRandomValues on older browsers; the random part of v7 also comes from crypto.getRandomValues, which is just as secure. It is fast too: on our test computer the browser produced a million in under a second.

Do I need to sign up or pay?

No. The site is completely free, needs no account and has no usage limits.