About rusty-apps

rusty-apps is a growing collection of small, single-purpose tools — a cipher solver, a unit converter, a loan calculator, a colour and contrast checker, text and date tools, and dozens more. Each does one job and does it well, and each runs entirely inside your browser.

Everything runs on your device

Every tool is compiled to WebAssembly and runs in the browser tab. There is no server to send anything to, and none of them makes a network request while it works — you can open your browser's network panel and watch: nothing goes out. Once a page has loaded it keeps working offline.

Honest by design

Each tool says plainly what it can and cannot do. A converter that would have to guess a value refuses rather than inventing one; a result that is an estimate says so; a tool that cannot do something on a web page says which and why. The aim is that you never have to wonder whether a number can be trusted.

No accounts, no tracking

There is no sign-up and no login. There is no analytics script, no fingerprinting and no cookies of our own. Your settings and your recent input are kept in your browser's own storage, on your machine, and are never transmitted. See the privacy page for the detail.

Free, and how it is paid for

The tools are free to use. Advertising on the pages pays for hosting them. The advertising network sets its own cookies and sees your IP address and the page you are on, as it does on any site — but it never sees what you type into a tool, because that text is never part of the page and is never sent anywhere. An ad blocker breaks none of the tools.

Built in the open, with Rust and WebAssembly

rusty-apps is a personal project by Peter Hlavaty. The tools are written in Rust and compiled to WebAssembly, and the same code also builds as a desktop application with no network access at all. Each group of tools lives on its own address, linked from the front page.

Contact

rusty-apps is built and maintained by Peter Hlavaty. Feedback and bug reports are welcome.