About this uuid generator
UUID Generator
A UUID generator creates universally unique identifiers — 128-bit values written as 32 hexadecimal digits in five groups — that you can use as database keys, API request IDs, filenames, or test data. Click once and the tool produces a version 4 UUID instantly, with no coordination or central registry required.
How to use it
- Click Generate to create a new version 4 UUID.
- Read the result in the UUID field — 36 characters in the 8-4-4-4-12 format.
- Click Copy to copy that UUID to your clipboard.
- For test data, set the Quantity (e.g. 100) and click Generate, then use Copy all to grab the batch.
The method behind it
Frequently asked questions
What is the difference between UUID v1 and v4?
Version 1 embeds a timestamp and the machine's MAC address, so IDs sort by creation time but leak hardware information. Version 4 is fully random, reveals nothing about the machine or time, and is the right default for almost everything. This tool generates version 4. If you need time-ordered IDs for database index performance, look into version 7 instead.
Can two UUIDs be the same?
In theory yes, in practice no. With 122 random bits there are about 5.3 × 10^36 possible version 4 UUIDs. You would need to generate on the order of 2^61 of them before a duplicate becomes likely — far more than any system will ever create. A collision would indicate a broken random number generator, not bad luck.
Are UUIDs secret? Can I expose them in URLs?
A version 4 UUID is unpredictable, so it works as an unguessable token (for example, a private share link) — but it is still just an identifier, not a password. Anyone who sees it can reuse it, so treat UUIDs in URLs like capabilities: fine for low-stakes sharing, not a substitute for authentication on sensitive resources.
Uppercase or lowercase — does it matter?
RFC 4122 specifies lowercase for the canonical form, and that is what this tool outputs. Hex digits are case-insensitive, so `C5E4B5FA-...` refers to the same UUID. Some systems normalize to lowercase on input; to avoid mismatches in string comparisons, store and compare them in one consistent case.
What is the nil UUID?
The nil UUID is all zeros: `00000000-0000-0000-0000-000000000000`. It is the "no value" sentinel defined by RFC 4122, useful as a default or placeholder in databases and APIs. This generator never produces it — every click yields a fresh random version 4 value.
Worked example
One click produced: c5e4b5fa-12b7-44b4-a355-8880bbe0e785.
Checking it against RFC 4122:
- 32 hex digits + 4 hyphens = 36 characters
- Third group
44b4starts with4→ version 4 - Fourth group
a355starts witha(1010in binary) → variant bits10 - Field breakdown:
time_low= c5e4b5fa,time_mid= 12b7,time_hi_and_version= 44b4,clock_seq= a355,node= 8880bbe0e785
All remaining 122 bits are random output from the browser's cryptographic generator. Paste it anywhere a UUID is expected — PostgreSQL, MySQL, MongoDB, and every major programming language parse this form directly.