Last updated · 29 Sep 2026

Privacy policy

Filt holds what you weigh, how you slept and how hard you trained. That is health data, and the law treats it as a special category for good reason. This policy says what we collect, why we are allowed to, who else ever sees it, how long we keep it and what you can make us do about it.

The short version: your feed is yours. We do not sell it, we show no advertising, we run no analytics or tracking, and nobody sees your entries unless you connect with them and choose to share.

1. Who is responsible

Interval Labs BV, registered with the Dutch Chamber of Commerce (KvK) under number 42139840, at Herengracht 551, Amsterdam, is the controller of the personal data described here. Write to hello@intervallabs.nl about anything in this policy.

2. What we collect

Your account. You sign in with Apple, and we receive an identifier for you there, plus your email address and your name if you let Apple pass those on. We store no password. You can set the name other people see and choose whether you read kilograms or pounds, kilometres or miles.

What you record. Your workouts and the exercises, sets, weights, times and heart rate in them. Your body measurements: weight, body fat, lean mass, height, waist. Your sleep and its stages. Your daily activity: steps, distance, active and basal energy, flights climbed, exercise minutes, stand hours, heart rate and resting heart rate, heart rate variability, respiratory rate, VO₂ max, blood oxygen. Notes you write and how you say you felt. Photos, videos and documents you attach, and the programs you follow.

What Apple Health hands over. On an iPhone, Filt reads what the phone and the watch have already measured and writes it into your feed, so you do not type it twice. It reads only the types you allow in the Health app, the reading happens on your device, and you can withdraw the permission in iOS whenever you like.

Your devices. For each device that is signed in we keep an identifier for it, whether it is an iPhone, an iPad or a browser, the name it gives itself, when it signed in and when it last reached us. If you turned notifications on, we also keep the token Apple gives us for reaching that device.

Who and what you connect to. The invitations you make or accept, who you are connected to and in what role, and any AI assistant or other app you have authorised, along with what you allowed it to read and write.

Server logs. Our server writes a line for each request: the time, what was asked for, the IP address it came from, and which account made it, if any. We use them to keep the service running and to investigate abuse.

No law obliges you to give us any of this, and no contract obliges you either. It is what Filt is made of, though: without an Apple sign-in there is no account, and without entries there is no feed. If you would rather not give it, the consequence is that you cannot use Filt.

3. Cookies

We do not track you. The website sets three cookies and every one of them is there to make it work: one keeps you signed in, one recognises your browser so a second sign-in replaces the first rather than piling up, and one lasts the few minutes a sign-in takes. There are no analytics or advertising cookies, and nothing follows you to another site. That is why you are not being asked to accept anything.

4. Health data

Most of what Filt holds is data about your health, which we may only process with your consent. You give it on your iPhone, in two places. The Apple Health screen says what turning the import on does — what Filt reads is stored on our server as part of your feed — before you turn it on, and turning it on is your consent to that. Writing an entry into Filt yourself is your consent to that entry. Both are yours to take back: turn the import off, change what you allow in the Health app, delete the entries, or delete your account. Withdrawing does not undo what we did while the consent stood, and it does not reach anyone who already read something you shared.

5. Why we are allowed to use it

• To run Filt for you, because you asked us to and that is our agreement (GDPR article 6(1)(b)).
• For your health entries, your consent on top of that agreement, given the way section 4 describes (article 9(2)(a)).
• To keep the service secure, available and free of abuse, which is our legitimate interest and yours (article 6(1)(f)).
• When the law requires it of us (article 6(1)(c)).

We make no automated decision that has a legal effect on you or anything like one. An AI assistant you connect may write training advice into your feed; that is advice from whoever runs it, and section 7 of the terms of use says the rest.

6. Who else sees it

• The people you connect with, and only what your sharing settings give them.
• Apple, who you sign in with. They learn that you signed in to Filt. They do not receive your feed.
• Apple, when we send a notification to your phone or watch. A notification carries the text you would read on the lock screen.
• Scaleway, who host the server, the database and the files for us in the Netherlands.
• Any AI assistant or app you have connected, acting for you and only within what you allowed. What it then does with what it read is the business of whoever runs it.
• Authorities, if the law obliges us. We will tell you it happened unless we are forbidden to.

Nobody else. We do not sell personal data, we do not pass it to advertisers or data brokers, and we do not use it to train anything.

7. Where it is kept

Everything lives in the Netherlands: the server, the database, the private buckets holding your files and the continuous backup of the database. Two exceptions leave the EU by their nature. Signing in involves Apple, and notifications go through Apple's push service. Apple is an American company, and the safeguards it applies to those transfers are the ones it publishes itself, in Apple's privacy policy and the transfer terms it names there.

8. How long we keep it

• Your account and everything in it, for as long as your account exists.
• The catch-up log that lets a device that has been offline get back in step, 30 days.
• Server logs, two weeks, then they are deleted.
• An upload no entry refers to, one day, then it is swept away.
• The continuous backup of the database, 30 days. A deletion reaches the live database at once and is gone from the backup within a month.

Deleting your account deletes your feed, your files, your devices and your connections. You can do it yourself, on your account page or in the app, or ask us at hello@intervallabs.nl. What someone you shared with already saw, or already saved on their own device, stays with them.

9. Your rights

Under the GDPR you can ask us for a copy of what we hold about you, have it corrected, have it deleted, have our use of it restricted, receive it in a portable form, object to our using it, and withdraw a consent you gave. Write to hello@intervallabs.nl and we will answer within a month. It costs you nothing.

If we handle it badly, you can complain to the Dutch data protection authority, the Autoriteit Persoonsgegevens (autoriteitpersoonsgegevens.nl), or to the authority in the EU country you live in.

10. Age

Filt is for people of 16 and over. That is the age at which you can consent to this yourself under Dutch law. If we find out an account belongs to someone younger, we delete it.

11. How we protect it

Traffic between your devices and us is encrypted. We keep no passwords, because the sign-in providers hold them. Each device has its own session, and signing out of the website ends that session on our side, not just in the browser. Your files sit in a private bucket and are reached through links that expire, minted only for someone allowed to see them.

12. Changes to this policy

We may change this policy. If a change matters to you, we will tell you at least 30 days before it takes effect, by email or in the app, and the date at the top always says when this version was written.