Privacy policy of Hierro and Hierro Office
Last updated: 12 October 2026 · Version 2 · The Spanish version is the original; this is a faithful translation.
In short
- Hierro works without an account: without one, your data stays on your device and we do not receive it.
- With an account (optional), your data is stored on servers in the European Union (Ireland) so it can sync and, if you choose, be shared with your trainer.
- Your health data is processed only with your explicit consent, which you can withdraw at any time.
- Your trainer can only see you if you enter their code, sees only what is detailed below and changes nothing unless you accept it.
- We use no analytics or tracking of our own, there is no artificial intelligence and we do not sell your data.
- Ads exist only in the free Android app, with your consent, and never during a workout.
- You can download your data and delete your account instantly.
1. Who is responsible
The controller of your data is Jonathan Torres Martin, Spanish tax ID (NIF) 22766528R, who provides Hierro (gym notebook: Android app and web app at app.hierroapp.com) and Hierro Office (web app for trainers at office.hierroapp.com), as well as the website hierroapp.com.
Contact for any privacy matter: soporte@hierroapp.com.
2. What data we process, why and on what basis
Without an account we do not receive your training data: your routines, workouts, weight and height are only on your device. This is what we process if you create an account or use the services described:
Creating and maintaining your account
Data: email address, name, password (stored protected by an irreversible hash; we cannot see it) and an internal identifier. If you sign in with Google, Google sends us your email, your name and your Google profile picture (we do not use the picture); we do not receive your Google password. The name is optional when you sign up; if you do not enter one, we provisionally use the part of your email before the “@”. To connect with a trainer you will have to enter a name.
Legal basis: performance of the service you request (Art. 6(1)(b) GDPR). Period: while you have the account.
Syncing your training data
Data: routines, workouts (exercises, sets, reps, weights, notes), settings and body weight.
Legal basis: performance of the service (Art. 6(1)(b)) and, because it is health data, your explicit consent (Art. 9(2)(a)). Period: while you have the account.
Linking with a trainer
Data: the link with your trainer, the notes and change proposals they send you, the health questionnaires (PAR-Q) you answer and the dates on which they ask for your weight.
Legal basis: your explicit consent when you redeem their code (Art. 9(2)(a)), with details of what they will be able to see. Period: until you unlink or delete your account.
Trainer account (Hierro Office)
Data: email, name, plan and validity, templates, agenda, preferences and, once paid plans exist, billing data.
Legal basis: performance of the service (Art. 6(1)(b)) and, for invoices, legal obligation (Art. 6(1)(c)). Period: while you have the account and, for billing, as long as the law requires (up to 6 years).
Ads (free Android app only)
Data: the device advertising identifier, IP address and technical data, processed by Google (see section 6).
Legal basis: your consent (Art. 6(1)(a)) in the European Economic Area and the United Kingdom. Period: managed by Google.
“Remove ads” purchase
Data: an anonymous identifier and the purchase receipt, received by RevenueCat.
Legal basis: performance of the contract (Art. 6(1)(b)). Period: as long as the law requires for proof of purchase.
Support
Data: the email you send us and whatever you tell us in it.
Legal basis: handling your request and our legitimate interest in replying (Art. 6(1)(b) and 6(1)(f)). Period: as long as needed to resolve your query.
Operation and security of the websites
Data: technical logs (IP address, date, page requested) generated by the hosting provider when serving the sites.
Legal basis: our legitimate interest in keeping the service secure (Art. 6(1)(f)). Period: a few days, depending on the provider.
We do not ask for your location, contacts, body photos or microphone. We use no analytics or tracking of our own, and we do not take automated decisions with legal effects about you or build profiles of you (except Google’s ad personalisation, if you accept it).
3. Health data and consent
Your weight, your workouts and your PAR-Q answers are data concerning health, a special category under the GDPR. We process them on our servers only with your explicit consent, which you give when you create the account to sync them and when you redeem a trainer’s code, at which point you see what they will be able to view before accepting.
You can withdraw your consent at any time, without affecting processing done before: by unlinking from your trainer (they stop seeing your data immediately) or by deleting your account. If you do not want your data to leave your device, use Hierro without an account.
4. What your trainer sees
While the link is active, your trainer sees your name, your routines, your workouts, your body weight and your answers to the questionnaires they sent you. They do not see your email, your settings or anything else. To connect with a trainer we ask for a name: it is the one they will see, and you can change it any time in Settings. Your trainer never changes your routine directly: they send a proposal that you accept or decline, and you can unlink whenever you want.
Once your trainer accesses your data or exports it (PDF, CSV, images), they are the controller of that copy and must comply with data protection law. We are the provider of the tool.
5. If you are a trainer (Hierro Office)
For your own account, we are the controller. For your clients’ data that you view, export or enter (notes, proposals, agenda), you are the controller and we act as processor on your behalf: we process it only to provide you the service, following your instructions, and the providers in section 7 act as sub-processors. It is your responsibility to inform your clients and to have a legal basis to process their data. If you need a written data processing agreement, ask for it at soporte@hierroapp.com.
Paid Hierro Office plans will be charged through an external payment provider (Stripe): we do not see or store your card details.
6. Ads and purchases
Ads. The free version of the Android app shows ads from Google AdMob. For this, Google may process the device advertising identifier, the IP address and technical device data. In the EEA and the UK, Google asks for your consent before showing ads, using its own form, and you can choose non-personalised ads. You can change your choice, or reset or delete the advertising identifier, in your phone’s Google settings (“Ads” section). More information: how Google uses data.
Ads never appear while you are working out. You will not see them if your trainer has an active plan or if you buy “remove ads”. The Hierro web app (app.hierroapp.com), Hierro Office and hierroapp.com do not show AdMob ads.
“Remove ads” purchase. Payment is handled by Google Play; we do not see your payment details. To verify the purchase we use RevenueCat, which receives an anonymous identifier and the receipt.
7. Who we share data with
We do not sell your data or use it for advertising of our own. We share it with these providers, only for the stated purpose:
| Provider | Purpose |
|---|---|
| Supabase (servers in Ireland, EU) | Database, sign-in and account emails (confirming your email, resetting your password) |
| Cloudflare | Hosting of the websites and Hierro Office, domain and forwarding of the support email |
| Google (AdMob, Google Play, Sign in with Google, Gmail) | Ads, app distribution and purchases, signing in with your Google account and receiving the support email |
| RevenueCat | Verifying the “remove ads” purchase |
| Stripe (once paid plans exist) | Charging for trainer plans |
Your trainer also receives the data detailed in section 4, only if you link them. We may disclose data to authorities when the law requires it.
8. Transfers outside the EU
Some providers (Google, Cloudflare, RevenueCat, Supabase and Stripe as parent companies) are or may process data outside the European Union, for example in the United States. When that happens they rely on GDPR safeguards: an adequacy decision (EU–US Data Privacy Framework) or standard contractual clauses. Account data is stored in the EU (Ireland).
9. How long we keep it
- Your account and data: while you have the account. When you delete it (Settings → Your account → Delete my account), your profile, routines, workouts, weight, notes, proposals, questionnaires and links are removed immediately. The provider’s technical backups may take up to 30 days to disappear.
- Billing and receipts: as long as the law requires (up to 6 years). Deleting your account does not cancel subscriptions: cancel them first in Google Play or in the payment portal.
- Support: as long as needed to resolve your query.
- Data only on your device: you keep it until you delete it or uninstall the app.
10. Your rights
You can exercise your rights of access, rectification, erasure, restriction, objection and portability, and withdraw your consent at any time. In the app you can download a copy of your data (Settings → Download copy) and delete your account yourself. For any other request, write to soporte@hierroapp.com from your account email, so we can confirm it is you; we reply within one month. Without the app, you can delete your account by following these instructions.
If you believe we have not handled your data properly, you can complain to the Spanish Data Protection Agency (aepd.es) or to the authority in your country.
11. Your device, cookies and permissions
Storage on your device. The apps and websites store on your device (local storage of the browser or app, and the browser cache) your data, your settings and the files needed to open them offline. This is essential for them to work. We use no tracking or advertising cookies on hierroapp.com, app.hierroapp.com or office.hierroapp.com. If you sign in with the Google button, Google may use its own technical cookies to manage the sign-in.
Android app permissions. Internet; notifications, exact alarms and vibration, for the rest timer; and the advertising identifier, for the free version’s ads. It does not access your location, contacts, camera, microphone or files.
Backups and files you create. If you download a backup or share an image of a workout, the file is saved or shared wherever you choose: it does not go through us.
12. Security
Connections are encrypted (HTTPS) and the database provider encrypts stored data. Each person can only access their own rows: a client only sees their own data and a trainer only sees the clients linked to them. If there were a security breach affecting you, we will tell you and notify the supervisory authority where required.
13. Minors
Hierro is not aimed at children under 14 (or under 16 in countries whose law requires that age to consent to data processing). If you believe a minor has created an account, write to us and we will delete it.
14. Changes and contact
If something important changes, we will tell you in the app and update the date and version above. For any privacy question: soporte@hierroapp.com.