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Privacy Policy

Last updated: 10 September 2026

Inertia Training ("the app", "we") is a companion app for intervals.icu. This policy explains what data the app and this website handle, why, and how you can remove it.

Account data

Creating an account requires an email address and password, handled by our authentication provider (Supabase). We do not see or store your password in plain text. If you sign in with Apple or Google instead, we receive only the email address that provider releases to us, never your provider password.

Beta waitlist

If you ask for beta access on this website, we store the name and email address you type into that form, and nothing else. We use them only to send you a TestFlight invitation and to tell you when a place is free. Joining the waitlist does not create an account, and we do not add you to any other list.

A waitlist entry is separate from an account, so deleting your account in the app does not remove it. To come off the list at any time, email support@inertia.training and we will delete your entry.

Your intervals.icu connection

To read your training data, the app needs permission to reach your intervals.icu account. There are two ways to give it. Most people connect with intervals.icu's own authorisation screen, which sends us an access token limited to the permissions listed there. You can also paste a personal API key instead.

Either way, the credential is stored securely on our server and is never sent to or stored on your device. Every request to intervals.icu is made on your behalf through our server. The app itself only ever knows whether a connection exists, and, for an API key, the last four characters so you can recognise which key is saved. You can withdraw the authorisation at any time from your intervals.icu account settings.

Training and health data

Your activities, planned workouts, wellness data and training history are read live from your intervals.icu account each time the app needs them. This includes fitness and health related measurements you have recorded there, such as heart rate, heart rate variability, resting heart rate, sleep, weight and perceived exertion. We do not keep a separate permanent copy of your training data on our servers beyond what is needed to serve that request.

Data stored on your device

So the app works without a connection and does not have to refetch everything each time you open it, recently viewed training data is cached on your phone. Your login session is held in the device keychain. Your display preferences, such as light or dark mode and metric or imperial units, are stored on the device too. All of this stays on your phone. Signing out clears the cached training data, and deleting your account clears everything the app has stored locally.

Location and maps

The app does not request access to your phone's location. If an activity you already recorded has a GPS route, the app draws that route using map tiles from MapTiler. Route coordinates come from your intervals.icu activity data. Loading map tiles means MapTiler receives your device's IP address and the map area being viewed, which is how any map on the internet works. We do not store your routes separately.

Crash and error reporting

We use Sentry to capture crash reports and errors so we can fix bugs. This includes technical information like device type, OS version, and app version, plus the details of the error itself. We do not enable session replay, and we have deliberately turned off the option that would attach personally identifying information to these reports.

Product analytics

The app does not currently collect product or usage analytics. If we add them, we will update this policy first, the collection will be limited to screen names, counts and settings rather than your training content, and you will be able to turn it off.

Email

We send transactional email only, meaning account confirmation and password reset messages, through our email provider (Resend). If you joined the beta waitlist, we also email you about beta access, which stops as soon as you ask us to remove your entry. We do not send marketing email and we do not run a newsletter.

Password safety check

When you set a password, we check it against a public list of known breached passwords using a privacy-preserving method called k-anonymity. Your actual password never leaves your device; only a short, non-reversible partial hash is sent for the check.

Who we share data with

We do not sell your data. We share it only with the service providers needed to run the app, each handling a specific job on our behalf:

• intervals.icu, the source of your training data.
• Supabase, for accounts, authentication and secure storage.
• MapTiler, for map tiles on activities that have a route.
• Sentry, for crash and error reports.
• Resend, for account and password reset email.
• Apple and Google, if you choose to sign in with them. Apple also receives your email address if we send you a TestFlight invitation for the beta.

These providers may process data in countries other than your own. We may also disclose data if required by law.

What we don't do

• We don't run ads or third-party advertising trackers.
• We don't sell or share your data with data brokers.
• We don't post to intervals.icu or anywhere else without your action.
• We don't ask for access to your phone's location, contacts, photos or health app.

How long we keep data

Your account record and stored intervals.icu credential are kept until you delete your account, at which point they are removed immediately. Crash reports are kept for a limited retention window by Sentry and then deleted automatically. Cached training data on your device lasts until you sign out, delete the app, or delete your account. Beta waitlist entries are kept until the beta ends or you ask us to remove yours, whichever comes first.

Your rights

Depending on where you live, you may have the right to access, correct, export or delete the personal data we hold about you, to object to or restrict how we process it, and to complain to your local data protection authority.

Deletion is available to everyone directly in the app, described below. Export of the account data we hold, your email address and account metadata, is available on request: email support@inertia.training and we'll send you a copy in a portable format within 30 days. For anything else, including access or correction requests, email us and we will respond.

The training data itself, activities, wellness metrics, and zones, lives in your intervals.icu account rather than ours. intervals.icu has its own export tools, so requests about that data are best made there directly.

Deleting your account

You can permanently delete your account at any time from Profile → Delete Account. This removes your account record from our systems immediately, including your email address and your stored intervals.icu credential, and it clears what the app has stored on your device. If you connected with intervals.icu's authorisation screen, we withdraw that authorisation on the way out, so Inertia stops being listed as a connected app there.

Deleting your Inertia account does not affect your intervals.icu account or the training data stored there. Those stay separate and untouched. If you also joined the beta waitlist, that entry is stored separately and is not removed by deleting your account, so email us if you want it gone too.

Children's privacy

Inertia Training is not directed at children under 13, and we do not knowingly collect data from them. If you believe a child has created an account, email us and we will remove it.

Changes to this policy

If this policy changes, we'll update the "Last updated" date above. Continued use of the app after a change means you accept the updated policy.

Contact

Questions about this policy or your data? Email support@inertia.training.