Generate UUID v1/v4 identifiers
The MailDrop UUID generator produces universally unique identifiers on demand, right in your browser. You can choose between UUID v4, which is fully random, and UUID v1, which is derived from a timestamp, then generate up to 50 identifiers in one batch. An uppercase option formats the output to match style conventions in your codebase, and a single click copies the entire list to your clipboard.
UUIDs are the workhorse identifiers of modern software: database primary keys, API request IDs, session tokens, file names, and message correlation IDs all rely on them. Because v4 UUIDs are generated with the cryptographically secure randomness built into your browser, the chance of two identifiers colliding is negligible for any practical workload, and nothing you generate is sent to our servers.
The tool is free, requires no registration, and works offline once the page loads. Developers who test signup flows often combine it with MailDrop temporary email, using disposable email addresses alongside generated UUIDs to keep test data cleanly separated from personal information.
Select v4 for random identifiers, which is the right choice for most applications, or v1 if you want identifiers that embed a timestamp component and sort roughly by creation time.
Enter how many UUIDs you need, from 1 to 50 per batch. Generating in bulk is useful for seeding test databases or preparing fixtures ahead of time.
UUIDs are conventionally lowercase, but some systems and style guides expect uppercase hexadecimal. Tick the Uppercase box before generating to match the format your project requires.
Click Generate to fill the output box with one UUID per line, then use the Copy All button to move the whole batch to your clipboard for pasting into code, configs, or spreadsheets.
UUID v1 is built from a timestamp plus additional bits, so it encodes roughly when it was created and sorts in near-chronological order. UUID v4 is generated almost entirely from random data. Use v4 when you want no information leakage from the identifier itself, and v1 when time-ordering is helpful.
In theory yes, in practice no. A v4 UUID has 122 random bits, meaning you would need to generate roughly a billion UUIDs per second for decades before a collision becomes even remotely likely. For databases, APIs, and test data, you can treat them as unique.
No. Generation happens entirely in your browser with JavaScript, and the identifiers never reach our servers. There is nothing for us to store, log, or analyze. If you need to keep a batch, copy it before leaving the page, because refreshing produces a new set.
Yes for most uses. The v4 output uses the cryptographically secure random source in your browser, which is the same quality of randomness recommended for production UUIDs. That said, for identifiers generated server-side at scale, your language or database runtime typically has a native UUID function that fits better into your pipeline.
When testing registration or email workflows, developers often need unique throwaway values. Pairing generated UUIDs with MailDrop disposable email addresses lets you create fully synthetic test accounts, so no personal data ends up in staging systems and cleanup is as simple as letting the temp mail inbox expire.