UUID Generator

Version 4 UUIDs have 122 random bits, so the chance of a repeat is practically zero, even across billions of IDs made by different systems. You'd need to generate an enormous number every second for many years before a duplicate became likely. That's why they're safe to create without checking a central list.

Yes. The UUIDs come from the browser's cryptographic random number generator, crypto.getRandomValues, not from Math.random, which is predictable. If your browser can't provide secure random numbers, the tool says so and refuses to generate weak IDs. Any current browser supports it. Every UUID uses fresh random bits.

Yes. GUID is Microsoft's name for the same 128-bit identifier. Windows tools and .NET often show GUIDs in uppercase and wrapped in braces, like {3F2504E0-4F89-41D3-9A0C-0305E82C3301}. Tick the uppercase and braces options to get that exact style for registry keys or config files. The underlying value is the same.

No. They exist only in your browser tab. Nothing is sent to our servers, and they disappear when you close the page. That means nobody else has a copy of the IDs you generate. Copy or download them before closing the tab if you need them later.

Thirty-two hexadecimal digits in five groups separated by dashes, such as 550e8400-e29b-41d4-a716-446655440000. The 4 at the start of the third group marks version 4. Tick 'No dashes' to get the same value as one continuous string of 32 characters, which some systems prefer. Every UUID has the same length.

Between 1 and 1,000 per batch. Press Generate again for another batch. 'Copy all' puts the whole list on your clipboard, one per line, and the download saves them as uuids.txt. That's enough for most test data, imports and spreadsheet work in one go. Each batch is fresh.

They work well when IDs are created in many places, such as mobile apps or several servers, and when you don't want IDs to be guessable. They're larger than whole numbers and random order can slow some indexes. Many teams use them as public IDs and keep a number internally.

It's better not to. A v4 UUID is random, but it's designed as an identifier and often appears in logs, URLs and screenshots. For password reset links, API keys and session tokens, use a dedicated secure token with more randomness and handle it as a secret.

Version 1 uses time and the machine's address, version 4 is random, and the newer version 7 starts with a timestamp, so IDs sort by creation time. This tool makes version 4, the most widely supported. Check whether your database or framework prefers version 7 for new tables.

Some systems store UUIDs as a 32-character string without dashes, or as raw bytes, to save space. Others, such as certain APIs or file names, simply don't allow dashes. The value is the same either way. Tick 'No dashes' to match the format your system expects.

Yes. Copy all and paste into a column; each UUID lands in its own row. Format the column as text so the spreadsheet doesn't try to read any part as a number. That's a quick way to add unique IDs to a list before importing it into another system.

No. Hexadecimal digits mean the same in either case, so a UUID in capitals is the same ID as in lowercase. The standard prefers lowercase output, while Windows tools often show uppercase. Some databases compare text exactly, so store them consistently in one case. Pick one for your project.

Only to load the page. UUIDs are generated by your browser, so once the tool has loaded you can disconnect and keep generating. That also shows nothing is being fetched from or sent to a server. It works the same in any modern browser on any device.

Yes. Set the number, choose the format, press Generate and copy all. The list is easy to paste into a notes app, a message or a form on your phone. It runs in any modern mobile browser with no app and no account needed at any point.

Yes. It's free with no sign-up and no limit on use. It's one of the free developer tools from Marketiism, along with the password and hash generators and the Unix timestamp converter. Marketiism builds Marketiism for small businesses in India. Use it as often as you need, for any project.