Whetstone. Last updated 25 August 2026.
The short version. Whetstone is a training app for adults. It is not a medical device and it does not treat anything. We do not promise it will do anything for you. Use it sensibly, and if your concentration genuinely worries you, talk to a doctor rather than an app.
This summary is not the agreement. The rest of the page is.
Whetstone is made by Citadel of the Mind Software LLC, a California limited liability company. In these terms, “we”, “us” and “our” mean that company.
By using Whetstone you agree to what is on this page. If you do not, do not use it. Together with the Privacy Policy, this is the whole agreement between us about the app.
Whetstone is for adults. You may not use it if you are under 18, and by using it you confirm that you are not. We ask this at first run, and the app takes your answer at face value rather than verifying it — which is why it is stated here as a term rather than only as a question.
Whetstone is a general wellness product. It provides a training game, a breath practice, and a periodic task that measures how you did at that task.
It is not a medical device. It does not diagnose, treat, cure, mitigate or prevent any disease or condition, including any attention, learning or psychiatric condition. Nothing in the app, on this site, or in any of our materials is medical advice, and none of it is a substitute for a qualified professional.
If your concentration, memory or mood genuinely worries you, that is a conversation to have with a doctor. Do not use this app in place of one, and do not delay getting advice because of anything you read here or saw in the app.
We have run no clinical study of Whetstone and we do not claim any regulatory clearance or approval for it. Where the app explains why a task is built the way it is, it cites published research about those tasks. Those studies are not studies of Whetstone, and we do not present them as evidence that Whetstone works.
We do not promise that using Whetstone will do anything for you. We make no claim that it will improve your attention, your concentration, your memory, your work, your studies, your sport or any other part of your life, and nothing anyone says on our behalf should be read as making one.
The numbers Whetstone shows you describe how you did at Whetstone’s own tasks. They are not a measure of your attention in general, they are not a diagnosis, and they are not a prediction about anything outside the app.
Sessions ask for continuous attention for several minutes at a time. Do not use Whetstone while driving, operating machinery, or doing anything else that needs your attention. If you have photosensitive epilepsy or any condition affected by moving visual displays, take advice before using it. Stop if it causes you discomfort, eye strain or distress.
You may use Whetstone for your own personal, non-commercial use. You may not copy, resell or redistribute it, take it apart to extract its content, interfere with how it works, try to reach data belonging to anyone else, or use it in a way that breaks the law.
Whetstone, its content, its design and its software are ours and stay ours. Nothing here gives you any rights in them beyond using the app.
What we collect, why, who else sees it, and how to delete all of it is in the Privacy Policy. Two things worth repeating here: there are no accounts and we never ask for an email address, and deleting everything is a single button in Settings.
Because there is no account, there is no recovery. Your history lives with the anonymous identifier on your device. Lose the device, clear Whetstone’s stored data, or delete everything, and it is gone — we cannot restore it, because we have no way to know it was yours. That is a deliberate trade for collecting nothing that identifies you, and it is a real cost you should know about before you build up a history.
Whetstone is provided “as is” and “as available”, without warranties of any kind, whether express or implied, including any implied warranty of merchantability, fitness for a particular purpose, or non-infringement. We do not warrant that it will be uninterrupted, error-free, or that any data will be preserved.
Some states do not allow the exclusion of certain warranties, so parts of this may not apply to you.
To the fullest extent the law allows, we are not liable for any indirect, incidental, special, consequential or punitive damages, or for any loss of data, arising out of your use of Whetstone. Our total liability to you for any claim relating to the app is limited to the greater of the amount you paid us for it in the twelve months before the claim, or fifty US dollars.
Some states do not allow these limits, so parts of this may not apply to you. Nothing here limits liability that cannot lawfully be limited.
You can stop using Whetstone whenever you like, and delete everything from Settings. We may suspend or stop providing the app, in whole or in part, at any time. If we discontinue it, we will say so on this page.
If we change them, the date at the top changes and the current version is always here. Continuing to use the app after a change means accepting it. If a change is significant, we will say so in the app rather than relying on a page you never revisited.
These terms are governed by the laws of the State of California, without regard to its conflict-of-laws rules. Any dispute goes to the state or federal courts located in California, and you and we each agree to those courts.