Terms of use

1. These terms

These terms are an agreement between you and MPL Ventures, LLC, 330 N Wabash Ave, Floor 23, Chicago, IL 60611-7619, United States ("we", "us", "our"). They govern your use of the website at chess411.com, the Chess411 application for iPhone and iPad, listed on the App Store as Chess411 - Puzzles & Analysis, and the Chess411 application for Android on Google Play. We refer to these together as the Service.

By using the Service you accept these terms. If you do not accept them, do not use it.

Where you obtained the app from the Apple App Store and we have registered these terms with Apple as our custom licence agreement for your region, they also operate as the end user licence agreement for the app in place of Apple's standard licence agreement. Section 19 sets out the additional provisions Apple requires.

2. Who can use the Service

You must be at least 16 years old to use the Service. If you are under the age of majority where you live, you may only use the Service with the involvement of a parent or guardian, who accepts these terms on your behalf.

3. The Service is in beta

Parts of the Service are marked as beta. Beta features may change, break or be withdrawn without notice, and we make no promise that they will behave consistently or that data associated with them will survive. Where a feature is marked beta, treat it as work in progress.

Nothing in this section affects any statutory right you have as a consumer. Section 17 covers that.

4. What the Service does

Chess411 provides chess engine analysis, a next move calculator, an analysis board, game review, puzzles, a daily challenge, position scanning from photographs, and reference and instructional material.

That is the whole of what we promise. The Service is a study and practice aid.

We do not guarantee that any evaluation, suggested move, puzzle solution or opening assessment is correct or optimal. Engine evaluations depend on search depth, hardware, engine version and the time available, and they change. Some of that analysis runs on our servers and some runs on your own device, which is faster or slower than ours and may reach a different answer. We do not guarantee that the Service will produce the same answer twice, that its evaluation matches any other engine or platform, or that any puzzle rating is accurate.

Your progress, streak and settings are stored on your own device and nowhere else. Deleting the app or clearing your browser's site data removes them permanently and we cannot restore them.

Where you submit a score to the daily challenge scoreboard, that score comes to us. We may remove or refuse any entry we reasonably believe was not achieved by playing the challenge as intended.

5. Independence from other chess organisations and platforms

Chess411 is an independent tool. It is not affiliated with, endorsed by, sponsored by, or in any way officially connected to Chess.com, LLC, Lichess or the Lichess organisation, the Fédération Internationale des Échecs (FIDE), or any chess federation, tournament organiser or online chess platform.

"Chess.com", "Lichess", "FIDE" and related names and logos are the trademarks of their respective owners. We refer to them only to describe what the Service works with and where information comes from. All rights in those marks belong to their owners, and nothing in these terms gives you any rights in them.

Where the Service imports games using a public interface provided by Chess.com or Lichess, it does so at your instruction and subject to those platforms' own terms and privacy policies. We are not a party to your relationship with them. You are responsible for complying with their terms when you use their interfaces through the Service.

6. Your licence to use the Service

We grant you a personal, non-exclusive, non-transferable, revocable licence to use the Service, including to install and use the app on devices you own or control, for your own non-commercial use.

Subject to Section 9, you may not:

• Copy, modify, translate or create derivative works of the Service
• Reverse engineer, decompile or disassemble the app, except where that restriction is prohibited by law
• Rent, lease, lend, sell, sublicense or otherwise distribute the Service
• Remove or obscure any proprietary or licensing notice
• Circumvent any technical measure that limits access to or use of the Service
• Use the Service to build or train a competing product
• Use the Service to harass, abuse or harm anyone

We own the Service itself, and its design, software, original content and instructional material are ours or licensed to us. Nothing in these terms transfers ownership of them to you.

7. Our engine and API servers

The Service's analysis features call servers we operate and pay for. Access to them is provided to you as part of the Service and for no other purpose.

You may not:

• Send requests to our servers by any means other than the Service itself, including by calling our endpoints directly
• Use scripts, bots, crawlers or any other automated means to send requests
• Send requests at a volume or rate that interferes with the Service for other people
• Build, operate or distribute any product, service, application, interface or integration that relies on our servers
• Resell, redistribute or provide access to our analysis, puzzles or other server responses to anyone else
• Extract, copy or reproduce our puzzle set or other server-provided data in bulk
• Circumvent, disable or interfere with any rate limit, bot check or other protective measure, including Cloudflare Turnstile
• Attempt to gain unauthorised access to our systems or probe them for vulnerabilities
• Submit a daily challenge score by any means other than playing, including by calling our endpoints directly or by automating play

We may impose rate limits, require a bot check, and suspend or withdraw access to our servers or to the Service, in whole or in part and with or without notice, where you breach this section or where we reasonably believe your use is harming the Service or its cost of operation.

If you want to build something that uses our analysis, write to us at the address in Section 22 rather than assuming the answer is no.

Stockfish is free software and you are welcome to run it yourself. Section 9 says where to get it. What this section restricts is use of our servers, not use of the engine.

8. Fair play

You are responsible for making sure that using an assistive tool is permitted by the rules and terms of any game, match, tournament or platform you play on. Many prohibit outside assistance during play, and the consequences of breaching those rules are between you and the organiser or platform concerned.

9. Open source components

The Service is built on open source software and artwork, including the Stockfish chess engine, its WebAssembly build, ONNX Runtime Web, and chess piece sets by a number of authors. Each is provided under its own licence.

Attribution, copyright notices and licence terms are published on the licenses and credits page, and in the app under Licenses. Stockfish is licensed under the GNU General Public License, version 3, a copy of which is at /stockfish/gpl-3.0.txt. Source code locations are given on that page.

Nothing in these terms limits, restricts or overrides any right granted to you by the licence of any open source component. Where these terms and such a licence conflict, that licence prevails in respect of that component. In particular, the restrictions in Section 6 apply to the parts of the Service that are ours, and not to your rights in the open source components under their own licences.

Where we distribute a component in object code or compiled form and its licence requires us to make the corresponding source available, the source is reachable from the page above. If it is not, write to us at the address in Section 22 and we will provide it by the means that licence requires.

10. Advertising

The Service is free. We expect to fund it with advertising.

If and when advertising is shown, you accept that it will appear. We do not control which advertisements are selected. We are not responsible for the products or services advertised, and an advertisement appearing is not an endorsement by us. Any dealings you have with an advertiser are between you and them.

How advertising uses your information, and how to change your choices, is set out in our privacy policy.

11. Paid subscriptions

Chess411 is free. There is no subscription, no in-app purchase, and no payment code of any kind in it. This section describes how a subscription would work if we introduce one.

Pricing and billing. The name of the subscription, what it includes, its duration, and the full amount you will be billed each period will be shown to you before you buy. Payment is taken by Apple or by Google Play, depending on where you obtained the app, and charged to the payment method on your store account. We never see or hold your payment details.

Auto-renewal. Subscriptions renew automatically at the end of each billing period at the then-current price, unless you cancel at least 24 hours before the period ends. Your store account is charged for renewal within 24 hours of the end of the current period.

Managing and cancelling. You manage and cancel your subscription in your Apple ID settings or your Google Play account settings, not in the app. We cannot cancel a subscription on your behalf. Deleting the app does not cancel a subscription.

Free trials. Where a free trial is offered, any unused portion is forfeited if you buy a subscription during the trial. Trials are limited to one per user unless we say otherwise.

Refunds. Apple and Google take the payment, so they handle refunds under their own policies and we cannot issue one directly. Tell us at [email protected] if something has gone wrong and we will help where we can, including by supporting your request to them.

Price changes. We may change subscription prices. Changes take effect at the start of your next billing period and we will give you notice, and the chance to cancel, in advance.

If we discontinue the Service while you hold a subscription, we will make good the unused part of your current billing period. Because Apple and Google control refunds, that may take the form of us asking them to refund you on our behalf, or of continued access for the remainder of the period. We will tell you which at the time.

12. Games, positions and images you provide

You are responsible for what you upload, paste or scan.

Do not upload images you do not have the right to use. Do not upload games or files containing personal information about other people where you have no basis to share it. Player names contained in a game file are information about those players, and our privacy policy explains what happens to them technically.

Providing a game, position or image to the Service gives us no ownership of it. We use it to produce the result you asked for and, as set out in the privacy policy, we do not store it.

13. Feedback and submissions

If you send us feedback, suggestions or ideas about the Service, you give us permission to use them freely to improve what we do, without owing you payment or credit. You keep whatever rights you have in what you sent. We simply need to be able to act on it without a later dispute over an idea we may already have been working on.

Please do not send us anything confidential, and please do not send us personal information about other people.

14. Links to other websites

The Service contains links to websites we do not control, including Chess.com, Lichess, open source project repositories and, in future, advertisers' sites. We do not check or endorse them, and these terms stop applying once you leave. Anything you do on those sites is between you and them.

15. Availability and changes

We may change, suspend or discontinue the Service or any part of it, including removing features or content, at any time. We may release app updates, and some updates may be required for the app to keep working.

We do not promise that the Service will be available uninterrupted or error-free. It depends on our servers, on third-party services and on your internet connection.

We may change these terms. Where a change is material we will bring it to your attention rather than relying on the date at the top of this page. Continuing to use the Service after a change takes effect means you accept it.

16. Disclaimers and liability

To the fullest extent permitted by law, the Service is provided "as is" and "as available", without warranties of any kind, whether express or implied, including implied warranties of merchantability, fitness for a particular purpose and non-infringement.

To the fullest extent permitted by law, our total liability to you arising out of or relating to the Service is limited to the greater of the amount you paid us in the 12 months before the claim arose, or twenty US dollars. We are not liable for indirect, incidental, special, consequential or punitive damages, or for lost profits or lost data, including progress, streaks or settings stored on your device.

Nothing in these terms limits liability that cannot be limited by law, including liability for death or personal injury caused by negligence, or for fraud.

17. If you are a consumer in the EU or the UK

Nothing in these terms affects your statutory rights as a consumer, and where these terms conflict with those rights, your rights prevail.

Right of withdrawal. You normally have 14 days to withdraw from a contract for digital content bought at a distance. Where you buy a subscription and ask for immediate access, you acknowledge that supply begins immediately and that you lose the right of withdrawal once supply has begun, to the extent permitted by law. Apple and Google apply their own refund practices, which may be more generous.

Legal guarantee. You are entitled to digital content that conforms to the contract. If it does not, you may be entitled to have it brought into conformity, or to a price reduction or refund. Section 3 does not exclude this.

Disputes. You may bring proceedings in the courts of the country where you live, and the mandatory consumer protection law of that country applies to you regardless of Section 20.

18. Copyright complaints

If you believe material on the Service infringes a copyright you own or control, write to [email protected] with:

1. Your name, address and contact details
2. Identification of the work you say has been infringed
3. Identification of the material on our Service you are complaining about, with enough detail for us to find it
4. A statement that you believe in good faith the use is not authorised by the owner, its agent or the law
5. A statement that the information in your notice is accurate, and that you are authorised to act for the owner
6. Your physical or electronic signature

We take these seriously and will respond promptly. We may remove or disable access to material while we look into a complaint.

19. Apple and Google provisions

These provisions apply where you obtained the app from the Apple App Store or Google Play.

• This agreement is between you and us only, not with Apple or Google. We, not they, are solely responsible for the app and its content.
• Your licence is limited to using the app on devices you own or control, as permitted by the applicable store's terms of service.
• Neither Apple nor Google has any obligation to provide maintenance or support for the app.
• If the app fails to conform to any applicable warranty, you may notify the store, and the store may refund the purchase price. To the maximum extent permitted by law, neither has any other warranty obligation.
• We, not Apple or Google, are responsible for addressing any claim that the app or your use of it infringes a third party's intellectual property rights, and for any product liability, legal or regulatory claim relating to the app.
• Your use of the app must comply with any third-party terms of agreement that apply to it, including the terms of the open source components described in Section 9 and the terms of any wireless data service you use.
• You confirm that you are not located in a country subject to a US Government embargo or designated as a terrorist-supporting country, and that you are not on any US Government list of prohibited or restricted parties.
• Apple, Google and their subsidiaries are third-party beneficiaries of these terms and may enforce them against you.

20. Governing law

These terms are governed by the laws of the State of Illinois, United States, without regard to its conflict of law rules. The state and federal courts located in Illinois have exclusive jurisdiction, subject to Section 17 where you are a consumer in the EU or the UK.

21. General

You may stop using the Service and delete the app at any time. We may end your licence if you materially breach these terms.

If any provision is found unenforceable, the rest remains in force. Our failure to enforce a provision is not a waiver of it. You may not assign these terms; we may assign them in connection with a merger, acquisition or sale of assets.

Sections 5, 6, 7, 9, 16 and 20, and any accrued rights, survive termination.

These terms, together with the privacy policy, are the entire agreement between us about the Service.

22. Contact

MPL Ventures, LLC
330 N Wabash Ave, Floor 23
Chicago, IL 60611-7619
United States

[email protected]