UUID Generator
Generate cryptographically-random version-4 UUIDs — one or hundreds at a time. Copy or download them in a click.
Reviewed by the CalcCafe editorial team · Last updated 1 July 2026 · How we test our tools
How it works
Each UUID is produced with crypto.randomUUID() (or a crypto-random fallback), entirely in your browser.
100% client-side — nothing you paste is ever uploaded.
Frequently asked questions
Are these UUIDs random and safe?
Yes — they are version-4 UUIDs generated with the browser's cryptographic random source (
crypto.randomUUID), giving extremely low collision probability.How many can I generate?
Up to 500 at once. Use the copy or download button to grab them all.
People also ask
What is a UUID generator?
A UUID generator produces universally unique identifiers, 128-bit values written as 32 hexadecimal digits in a 8-4-4-4-12 pattern like 3f2504e0-4f89-41d3-9a0c-0305e82c3301. This one creates version-4 UUIDs, which are filled with random bits from the browser's crypto API, so the chance of two ever colliding is negligible. Use them for database keys, request IDs, or any place you need an ID without a central counter.
What does UUID mean?
UUID stands for Universally Unique Identifier, a 128-bit number standardized in RFC 4122 and its successors and written as 36 characters including four hyphens. It is called universally unique because the value space is so large (2 to the power of 122 random bits in version 4) that independent systems can generate IDs without coordinating and still not collide. GUID is Microsoft's name for the same thing.
What can hackers do with UUID?
A version-4 UUID like the ones generated here is random and reveals nothing about who or what created it, so knowing one only matters if your system treats the UUID alone as proof of access. Version-1 UUIDs are different: they embed a timestamp and historically the machine's MAC address, which can leak information. The real risk is using any UUID as a password substitute; use proper authentication and treat IDs as identifiers, not secrets.
When not to use UUID?
Avoid random UUIDs as primary keys in large tables where insert performance and index locality matter, because their randomness scatters writes across the index; a time-ordered ID such as UUID version 7 or ULID works better there. They are also a poor fit when IDs must be short, human-readable, or typed by hand, and they are not secrets, so never use one as an access token. For everything else, a version-4 UUID is a safe default.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.