Contact
Last updated: October 9, 2026
Leitner Learner (G5) is operated by Stackfully B.V.. For help with your account, billing, or privacy requests, reach us by email.
Support email
Please include the email address on your account and a short description of the issue. Billing enquiries should mention whether you paid through Paddle.
Billing and subscriptions
The initial release is free. Existing Pro subscriptions are managed through Paddle. You can update payment methods or cancel an existing subscription from Billing in the app when signed in. See our Refund & Cancellation Policy.