Contact
CardForge is run by one developer, so messages go straight to the person who can act on them.
Best for billing and subscription questions, account access problems, privacy and data requests, and anything you would rather not post in public. Expect a reply within a few days. It is one person, not a support desk, so if something is urgent say so in the subject line.
Discord
The fastest route for bug reports, feature requests, and questions about how something works. Other players are there too, which often means an answer before I have even read the message.
In the app
Every page has a feedback button in the bottom corner. It is the least effort of any option here and it tells me which page you were on when you hit the problem, which usually saves a round trip.
Press and creators
Logos, screenshots and background are on the press page. For review accounts or anything not covered there, email the address above.