What your period tracker knows about you
· 2 min read
Cycle apps hold some of the most sensitive data you generate. Here is what to check before trusting one.
A cycle app knows when you bleed, when you have sex, when you are trying to conceive, when you are anxious, when you are not sleeping. Very little else on your phone is comparable.
In 2021 the US Federal Trade Commission took action against a period-tracking app over sharing user data with third parties after telling users it was private. Whatever you think of any particular company, it established that this data is worth sharing to somebody — and that promises are not the same as architecture.
Questions worth asking of any tracker
Where is the data stored? On the device, or on the company's servers? If the app cannot function offline, it is generally the latter.
Can the company read it? "We encrypt your data" often means encrypted in transit and at rest on servers the company can decrypt. The stronger property is that the key never leaves your device — then reading it is not a matter of policy.
What happens on deletion? Does deleting the app delete the data, or does an account persist?
How is it funded? A free app with no subscription is being paid for somehow.
What does the App Store privacy label say? Apple requires disclosure of data linked to you. It is a quick and revealing read.
Where Sathi stands
Sathi keeps your history in a database on your phone and works fully offline. Backup is optional; when it is on, the bundle is encrypted on the device before upload with a key we do not hold. There is no screen in our admin tools that could show your symptoms, because what reaches us is ciphertext.
Export is free and always available. Deleting removes the account, the logs and the backups.
We would rather you checked that than took our word for it — which is the point of this page.