UUID Generator
Generate random version-4 UUIDs in bulk — uppercase or hyphen-free — or inspect one to read its version and variant. Free and entirely in your browser.
Generate UUIDs
Inspect UUID
🔒 Your code never leaves the browser — not one character is sent anywhere, and nothing is stored
How to use it
- Choose count and formatOne to 100 identifiers at a time, uppercase or lowercase, with or without hyphens.
- Copy the whole listThe copy button takes every generated identifier, one per line.
- Or paste your own UUID in the second boxTo inspect it instead of generating a new one — plain, hyphen-less or braced forms all work.
- Read its detailsVersion number, variant type, and whether it’s the nil UUID (all zeros).
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Frequently Asked Questions
Why use a UUID instead of a plain sequence number?
A sequential number (1, 2, 3...) needs a single central authority doing the counting, which becomes a problem when multiple servers or databases create identifiers at the same time without coordinating. A random UUID needs no coordination — any machine can generate one on its own with a near-zero chance of colliding with an identifier produced anywhere else.
What does "version 4", the one you generate, mean?
The UUID standard (RFC 4122) defines several versions that differ in where the bits come from: version 1 derives from the clock and the machine’s MAC address, version 5 is built by hashing a given string, and so on. Version 4 is fully random — 122 genuinely random bits from your browser’s Web Crypto — and it’s what about 95% of uses need: database keys, session identifiers, unique filenames.
Can you guarantee it will never repeat?
Mathematically, no — and no UUID generator on earth can guarantee that absolutely. Practically, though, the odds are negligible: you would have to generate more than 2.71 quintillion UUIDs (271 followed by 16 zeros) before a collision reached even 50% probability. That’s more than any real system will ever produce, so the practical guarantee holds even though the absolute mathematical one is impossible.
What does the "Inspect UUID" box show me?
We read the bits embedded in the UUID itself — its version and variant — and display them as-is, without judging whether it’s "correct" beyond the syntax. Even a UUID from another version (1 or 5, say) inspects fine and shows its true version. We never check for duplicates or look it up in a database — that would require access to yours, and we neither upload nor store anything.
Do you accept other formats like braces {} or urn:uuid:?
Yes. Some systems (like the Windows registry) wrap UUIDs in braces, the URN standard prefixes them with urn:uuid:, and some strip the hyphens entirely. The inspector recognizes all four forms automatically so you never have to clean the text up before pasting it.
Are the identifiers or any pasted text uploaded to a server?
No, not a single character. Generating and inspecting happen entirely inside your browser.