Darwin Terms of Use

Effective July 30, 2026 · Applies to the Darwin iOS app

These terms are an agreement between you and Justin Ramirez ("Darwin", "we", "us"), the developer of the Darwin app. By creating an account or using Darwin, you agree to them. If you don't agree, please don't use the app.

What Darwin is

Darwin builds an endurance training and fueling plan around a race date you choose, and rebuilds that plan each week based on the training you actually completed and the recovery data you provide. Training-load decisions are made by a deterministic planning engine. Where the app writes plain-language explanations, those explanations describe decisions the engine already made — they do not set your training.

Darwin is a planning tool for healthy recreational athletes. It is not a coach, a medical device, or a substitute for professional judgement.

Health, safety, and your own judgement

This section matters more than the rest, so please actually read it.

Darwin is not medical advice. It does not diagnose, treat, cure, or prevent any condition.
Consult a physician before starting or significantly changing a training program — particularly if you have or suspect a cardiovascular condition, are pregnant, are returning from injury or illness, are under 18, or have been advised to limit physical activity.
Endurance training carries inherent risk, including injury, illness, overtraining, heat illness, and in rare cases serious cardiac events. You accept those risks voluntarily.
You remain in control. Every session Darwin suggests is a suggestion. Stop immediately and seek medical attention if you experience chest pain, unusual shortness of breath, dizziness, fainting, or pain that feels like injury rather than effort. Never complete a prescribed session at the expense of your health.
Estimates are estimates. Training loads, heart-rate zones, readiness scores, and carbohydrate targets are calculated from the information you and your devices supply. They may be wrong, and they are not personalised medical or nutritional prescriptions. If you have a medical or dietary condition, work with a qualified professional.

Your account

You need an account so your plan survives a lost or replaced phone. You agree to provide accurate information, to keep access to your account secure, and to be responsible for activity under it. You must be at least 16 years old, or the age of digital consent where you live, whichever is higher. One person per account.

You can delete your account at any time from Account → Delete account in the app. Deletion is permanent and removes your plan and training history from our systems.

Subscriptions, billing, and cancellation

We think surprise charges are the worst thing a subscription app does, so here is exactly how ours works.

Pricing. Darwin is $9.99 per month or $79.99 per year in the United States. Prices in other countries are set by Apple's regional pricing and are shown in your own currency before you buy.
Free trial. New subscribers get a 7-day free trial. If you cancel before it ends, you are charged nothing. Trials are limited to one per Apple ID.
We will warn you before the annual charge. If you start a trial on the annual plan, we send a notification 3 days before it converts, naming the date and the amount. We are not obliged to do this; we do it because being ambushed by a large renewal is the single loudest complaint about our competitors. We do not send this reminder for the monthly plan, where the amount is small and the cancel button is one tap away in the app.
Auto-renewal. Subscriptions renew automatically at the price shown until you cancel. Apple charges your Apple ID within 24 hours before the end of each period.
Cancelling. Cancel any time from Account → Manage or cancel in the app, or in your iPhone's Settings → Apple Account → Subscriptions. There is no retention flow, no phone call, and no email required. Cancellation takes effect at the end of the period you have already paid for, and you keep access until then.
Refunds are handled by Apple, not by us, under Apple's Media Services terms. Request one at reportaproblem.apple.com. We will gladly support a refund request if the app failed you — email us.
Price changes. If we raise the price, Apple will notify you and, where required, ask for your consent before the new price applies. If you subscribed at an earlier price, you generally keep it while your subscription remains active.
What a lapsed subscription costs you. If your subscription ends, your current training week and every week you have already completed remain fully readable, including everything you logged. What pauses is the part you were paying for: the weeks ahead of the current one, the weekly re-plan, and the plain-language weekly read. Subscribing again restores them immediately. We do not delete your training history, and we do not hold it hostage.

Acceptable use

Don't do these things: reverse-engineer, decompile, or attempt to extract our source code or planning engine; resell, sublicense, or redistribute Darwin or the plans it produces as your own coaching product; use Darwin to provide paid coaching services to third parties without a written agreement with us; scrape or bulk-extract data from our systems; interfere with the service or attempt to circumvent subscription controls; or upload unlawful content.

Your data and your content

You own your training data. You grant us only the limited licence needed to operate the service for you — storing your plan so it syncs across your devices, and processing the weekly summary described in our Privacy Policy. We do not sell your data, show ads, or use your health data to train AI models.

We own Darwin itself: the app, the planning engine, the brand, and the content we write. You get a personal, non-transferable, revocable licence to use it while your subscription or trial is active.

Availability, changes, and beta software

Darwin is actively developed and parts of it are in beta. We may add, change, or remove features. If we make a change that materially reduces what you paid for, you may cancel and request a refund through Apple. We aim for the app to work offline for everything that matters — your plan is stored on your device — but we don't promise uninterrupted service, and cloud sync and the weekly digest depend on third parties.

We may suspend or terminate your access if you materially breach these terms. You may stop using Darwin at any time.

Disclaimers and limitation of liability

Except where the law does not allow it, Darwin is provided "as is" without warranties of any kind, express or implied, including merchantability, fitness for a particular purpose, and non-infringement. We do not warrant that the app will be error-free, that plans will produce any particular result, or that it will meet your goals.

To the maximum extent permitted by law, we are not liable for indirect, incidental, special, consequential, or punitive damages, or for lost profits, lost data, injury, or illness arising from your use of Darwin. Where liability cannot be excluded, our total liability is limited to the greater of the amount you paid us in the 12 months before the claim, or $100.

Some jurisdictions do not allow certain exclusions, so parts of this section may not apply to you. Nothing here limits liability for fraud, gross negligence, or anything else that cannot lawfully be limited. These terms do not affect your statutory consumer rights.

Apple-specific terms

Because Darwin is distributed through the App Store:

This agreement is between you and us only, not with Apple. Apple is not responsible for Darwin or its content.
Apple has no obligation to provide support or maintenance for Darwin. Support questions go to us.
If Darwin fails to conform to any applicable warranty, you may notify Apple, and Apple may refund your purchase price. Beyond that refund, Apple has no warranty obligation for Darwin.
Apple is not responsible for addressing claims relating to Darwin, including product liability, legal or regulatory non-compliance, or consumer protection claims.
If a third party claims Darwin infringes their intellectual property, we, not Apple, are responsible for handling that claim.
You confirm you are not located in a country subject to a U.S. Government embargo or designated as terrorist-supporting, and you are not on any U.S. Government restricted-parties list.
Apple and its subsidiaries are third-party beneficiaries of these terms and may enforce them against you.

Governing law and disputes

These terms are governed by the laws of the State of Delaware and the United States, without regard to conflict-of-law rules. If a dispute arises, please email us first — we would much rather fix a problem than argue about it. Nothing in this section prevents you from bringing a claim in a small-claims court, or from exercising rights that the law of your country of residence guarantees you.

Changes to these terms

We may update these terms. If a change is material, we will announce it in the app before it takes effect. Continuing to use Darwin after that means you accept the updated terms. The effective date at the top always tells you which version you are reading.

Contact

Justin Ramirez · justin@darwinendurance.com