Last updated May 2026.
These terms govern your use of Mainline. By using the app, you agree to them.
Mainline is a chess-training application that provides lessons, drills, and analysis to help you improve. It is for educational purposes and is not professional coaching or advice.
You are responsible for the activity on your account and for providing accurate information. You may use the app as a guest, but some features require an account.
Mainline offers an optional Pro subscription. Plans are a weekly plan at $5.99, a monthly plan at $9.99, and an annual plan at $49.99 (USD), each starting with a 7-day free trial.
Subscriptions renew automatically at the end of each period unless you cancel. Billing is processed securely by Stripe through RevenueCat; Mainline never stores your card details. Prices may change with reasonable notice.
You can cancel at any time from Settings or the billing portal. Cancellation stops the next renewal, and you keep Pro access through the end of the current period.
The 7-day free trial is not charged if you cancel before it ends. For refund requests, contact us at support@playmainline.com; refunds are considered on a case-by-case basis and may also be subject to the terms of the payment processor or app store used.
Do not misuse the service: no reverse-engineering, scraping, reselling, disrupting the service, or using it for unlawful purposes.
The lessons, drills, and other content in Mainline belong to Mainline or its licensors. Your own game data, and the public game data provided by chess.com or lichess, belong to you and to those platforms respectively.
Connecting a chess.com or lichess account is subject to those platforms' terms. Payments are subject to the terms of Stripe and RevenueCat.
Mainline is provided "as is," without warranties. We do not guarantee any specific improvement in your rating. Engine-backed analysis is provided to support your learning and may not be perfect. To the maximum extent permitted by law, Mainline is not liable for indirect or consequential damages arising from your use of the app.
These terms are governed by the laws applicable to the operator of Mainline, without regard to conflict-of-laws rules.
We may update these terms from time to time. The date above reflects the most recent version; continued use after an update means you accept the revised terms.
Questions? Email us at support@playmainline.com.