Support, from the source.
Every Derivative app is supported directly by the people who made it. Send a message and a human who actually built the thing will answer, usually within a couple of days.
Contact us
Tell us the app name and, if it helps, your iOS version.
Subscriptions & refunds
Handled by Apple: manage in Settings → Apple Account → Subscriptions, or reportaproblem.apple.com
Everything else
Send us a message