Terms of service

Service and accounts

The foundation line of each published opening is free and does not require an account. Additional lines in the same opening require an active premium membership or an eligible trial. The application shows access limits.

Use accurate account details, protect your sign-in and report unauthorized use. To subscribe, you must be legally able to enter a binding agreement; otherwise a parent or legal representative must do so. See the privacy notice for data processing details.

Subscriptions, prices and trial

Weekly, monthly and yearly plans provide access to the same premium opening library. USD base prices: $3.99 / week · $9.99 / month · $49.99 / year. Available local currencies and the final total with applicable taxes are shown at checkout before you commit. Check the currency and renewal frequency.

Eligible new customers receive a seven-day free trial. A payment method is required. Starting the trial authorizes automatic renewal: unless you cancel before it ends, you are charged the displayed price for your selected plan, then every week, month or year. Repeat trials may be prevented based on email or payment method. Creating an account alone does not start a trial.

Polar is the Merchant of Record for purchases and handles collection, applicable sales taxes, receipts/invoices and payment management. Transactions are also subject to the Polar Buyer Terms. Use of the ChessOpening service is governed by these terms.

Cancellation and refunds

Open the Polar customer portal through Account → Manage subscription to cancel online. Cancel before the trial ends to avoid the post-trial charge. Other cancellations normally take effect at the end of the current access period. Cancellation and refunds are separate actions. See our Cancellation and refund policy; non-waivable consumer rights remain protected.

License and acceptable use

You may use ChessOpening for personal learning within your free access or membership. Do not access other accounts, bypass access controls, disrupt the service, bulk-copy paid lesson data for resale, or use the service unlawfully. Openly licensed components and datasets remain subject to their own licenses; we do not claim exclusive rights over chess moves themselves.

Learning content and availability

Lessons, prepared explanations and engine evaluations are educational. We do not guarantee a particular Elo improvement, flawless move advice or uninterrupted availability. You can report content errors. If changes materially affect the service you purchased, applicable notice, cancellation and refund rights remain available.

Suspension, responsibility and disputes

We may restrict access where necessary and proportionate for security, fraud or a serious breach, and explain the reason and remedy where practicable. These terms do not exclude liability, consumer guarantees or remedies that cannot lawfully be excluded.

Contact support@chessopening.app first to help resolve a problem. Mandatory consumer law where you live and access to competent courts, consumer bodies and authorities remain available. Polar’s separate terms apply to the payment agreement.

Changes and privacy

We update this page’s date when terms change; changes materially affecting existing subscription prices or rights require applicable advance notice and consent. See our Privacy notice.