Contact form
Replies usually go out within a few days.
Reporting a wrong result
The quickest fix comes from three things: which tool you were using, exactly what you entered, and what you expected instead. A screenshot helps but is not needed.
Asking for a new tool
Requests are welcome. The one limit worth knowing up front is that anything needing a server — file hosting, scan tracking, saved accounts — falls outside what this site does, since every tool runs in the browser. Calculators, converters, generators and checkers are all fair game.