Contact
Corrections, bug reports and requests for new tools are all welcome. A short message saying what you expected and what happened is usually enough.
Reporting a wrong result
If a tool gave an answer you believe is wrong, include the input you used and the answer you expected. Since nothing you enter is sent anywhere, that context does not reach us unless you put it in the message yourself, and only include it if you are comfortable sharing it.
Why there is no form
A contact form needs a server to receive it. This site does not have one, and adding one just to collect messages would undercut the guarantee that nothing you type here is transmitted. Email is the honest option.