Contact
One address reaches the developer directly.
What to include
A tool is broken. Say which tool, what kind of file (type and rough size), which browser, and what happened. The file itself is no use and it is better not to send it.
A tool you wish existed. Describe the job in one sentence. This is what decides what gets built next.
Privacy requests under UK GDPR, EU GDPR or the California rules, and copyright notices, go to the same address. Replies come from it too.
Please do not send your documents. They cannot help with a bug report, and the site is designed so that nobody keeps a copy of them: the browser tools never send them anywhere, and the server tools delete them within 10 minutes.