Diastra
Effective 27 September 2026
The short version. Diastra is a heart rate training app for iPhone and Apple Watch, sold by Diastra LLC. It is a general wellness tool and never medical advice. A plan starts with seven days free and then renews by itself every month or every year until you cancel. You can cancel online at any time, and cancelling in the free week means you are never charged.
These terms are an agreement between you and Diastra LLC, 139 N Dobson Rd, Apt 404, Mesa, AZ 85201-6055, United States. They cover the Diastra iPhone app, the Diastra Apple Watch app, your Diastra account and the website diastra.app. Using any of them means you agree to these terms. For anything about them, write to support@diastra.app.
Diastra reads the heart rate and workout data your iPhone and Apple Watch already record, plans your training week, and shows how your heart responds to that training. Diastra is a general wellness product. It does not diagnose, treat, cure, prevent, predict or monitor any disease or medical condition, and it is not a medical device.
Version 1.1.1 and earlier of the app have no Diastra account; the account arrives with the next version. From that version on, everyone who uses Diastra makes an account, with a 6-digit code sent to an email address or with Sign in with Apple. There is no password. Keep access to that email address, because it is how you sign in and how a plan bought on diastra.app finds you.
You must be at least 16 years old to make an account, and at least 18 to buy a plan. An account is for one person. Give a real email address, and tell Diastra if you think someone else is using your account.
A plan bought on diastra.app is sold by Diastra LLC and paid through Stripe, Inc. It is offered in the United States only. The price, the free week and the renewal terms in the box at the top of this page are shown before you pay, and you agree to them when you start the plan. You get a receipt by email for every charge.
If Diastra ever changes the price of a plan, you get an email at least 30 days before the new price applies to you, and you can cancel before it does.
If a payment fails, Stripe tries again for a short time. If it still fails, the plan ends and Diastra stops working until a new plan starts.
A plan bought inside the Diastra app is sold and billed by Apple. Apple's own terms cover the payment, the renewal and any refund, and the plan is cancelled in iPhone Settings, under your name, then Subscriptions. Deleting the app does not cancel the plan.
One free week per person. An offer or code applies only as it says, and it cannot be exchanged for money.
If you are charged for a plan on diastra.app and write to support@diastra.app within 14 days of that charge, Diastra refunds it in full. After 14 days, charges are not refunded, and your plan keeps working until the end of the time you paid for. Refunds for plans bought in the App Store are handled only by Apple, at reportaproblem.apple.com.
Diastra LLC gives you a personal, non-transferable right to use Diastra for your own training while your plan is active. You may not copy, sell or rent Diastra, take apart its code, copy its content or data in bulk, get around its payment or sign-in, or use it to harm anyone. Diastra, its name, its mark, its words and its pictures belong to Diastra LLC.
If you send Diastra an idea or a feedback note, Diastra may use it to improve the product without owing you anything for it.
Diastra works out every number on your iPhone. When "Write my reads with AI" is on, those numbers are turned into sentences by Anthropic's Claude model, and every number in a sentence is checked against the numbers your phone worked out. A sentence can still be worded badly or miss something, so treat a read as information about your training and never as medical advice. You can turn the switch off in Profile, then Data & privacy.
The Privacy Policy says what Diastra collects, why, and how to delete it. It is part of these terms.
Diastra keeps changing. Features can be added, changed or removed, and a service Diastra depends on (such as Apple Health) can change what it allows. If Diastra ever stops being offered, anyone with a plan bought on diastra.app gets a refund for the time they paid for and did not get.
You can delete your account at any time in the Diastra app, under Profile, then Account, then Delete my account (in versions that have an account). Deleting the account cancels a plan bought on diastra.app. A plan bought in the App Store must be cancelled with Apple.
Diastra LLC can suspend or close an account that breaks section 7 or is used for fraud. Where it can, Diastra tells you why first and gives you a chance to fix it.
Diastra is provided "as is" and "as available". To the fullest extent the law allows, Diastra LLC makes no promise that Diastra will be error-free or always available, or that any training result will follow, and disclaims every implied warranty, including fitness for a particular purpose.
To the fullest extent the law allows, Diastra LLC is not liable for indirect, incidental, special or consequential losses, and its total liability for any claim is limited to the amount you paid for Diastra in the 12 months before the claim, or $50 if that is more. Some places do not allow these limits, and there they apply only as far as the law allows. Nothing in these terms limits a right the law says cannot be limited.
Arizona law governs these terms, apart from its conflict-of-law rules. Before any claim, write to support@diastra.app and give Diastra 30 days to fix the problem.
If the problem is not fixed, the claim is brought in the state or federal courts in Maricopa County, Arizona, and you and Diastra LLC agree to those courts. Either side may use small claims court instead.
These terms are between you and Diastra LLC, not Apple. Apple is not responsible for Diastra or its content, has no duty to provide maintenance or support for it, and is not responsible for any claim about it, including product liability, legal compliance or intellectual property claims. If the app fails to meet a warranty, you may tell Apple, and Apple will refund the purchase price of the app; Apple has no other warranty duty. You confirm you are not in a country under a US government embargo and are not on a US list of prohibited parties. Apple and its subsidiaries may enforce these terms as third-party beneficiaries. Where this section and Apple's Licensed Application End User License Agreement differ for an App Store purchase, Apple's agreement applies.
If these terms change, the date at the top changes with it, and the current version is always at this address. A change that affects your plan or your rights is emailed to you at least 30 days before it applies to you.