Your calendar stays yours.

Effective October 16, 2026. Applies to the Mayim Android app (package com.mayim.app), published by the Mayim developer ("we", contact below).

What Mayim is for

Mayim records information about menstrual flows, examinations (bedikos), the hefsek taharah, mikvah visits, births and related religious practices, and calculates calendar dates from them. This is sensitive health and religious information, and Mayim is designed so that we cannot read it.

Information stored on your phone

• Your calendar records, notes, the minhag (community practice) you choose, your chosen location (used only to calculate sunrise, sunset and nightfall) and your reminder preferences are stored on your phone.
• They are encrypted with a key held in your phone's Android Keystore. The records themselves are excluded from Android cloud backup and device-to-device transfer.
• You can export an unencrypted copy yourself ("Make a backup"); what you do with that copy is up to you.

Optional partner sync and cloud backup

If you choose Connect partner:

• Google sign-in. You sign in with your Google account through Google Firebase Authentication. Firebase receives your Google account's email address, name and profile identifiers and creates a Firebase user ID. We use these only to control who may access your shared calendar.
• End-to-end encryption. Before anything leaves your phone, each calendar record is encrypted with AES-256-GCM using a random key that exists only on your and your partner's phones. The key is passed to your partner only inside the private invitation link you send. Google's servers (Cloud Firestore) store only ciphertext. Neither we nor Google can read your dates, results, notes, location or minhag settings.
• What the server can see. To enforce access, the server stores the Firebase user IDs and sign-in email addresses of the (at most two) members of a shared calendar, an invitation's recipient email address until it is accepted or expires (7 days), the number and size of encrypted items, and the times they were written.
• Restoring on a new phone. So that signing in again brings your calendar back, Mayim saves the calendar key with Google's Block Store on your phone (included in your Google backup only when that backup is end-to-end encrypted with your screen lock). If you choose a Mayim PIN, the key is also stored on our server sealed with a value derived from your PIN on your phone; the server keeps only a random share and a keyed hash used to check PIN attempts, limits wrong attempts, and cannot open the key without your PIN. We cannot see or reset your PIN.
• Partner notifications. To tell your partner's phone that something changed, the server stores a Firebase Cloud Messaging token for each signed-in phone and sends a content-free "check for updates" message. The notification text is written on the receiving phone after decryption.
• Reminders are computed and scheduled on your phone. No reminder content is sent to any server.

Subscription and invitations

• Mayim is free for an initial period, then a subscription through Google Play. Google Play processes payment; we never receive your card details. The server stores your subscription status, its expiry, and a one-way hash of the Google Play purchase token to confirm it.
• To keep the free period and invitation rewards tied to your account, the server stores the date you started using Mayim, your invitation code, and for invitations a one-way hash of the invited person's sign-in email (to prevent double rewards).

What we do not do

• No advertising, no analytics, no crash-reporting services, no tracking, no sale or sharing of data with third parties.
• Mayim does not request your device location, contacts, camera, microphone or files.

Google Firebase processes the sign-in and encrypted sync data described above on our behalf as a service provider; see Google's privacy policy at policies.google.com/privacy.

Deleting your data

• On your phone: More → Minhagim & preferences → Erase this phone's records, or uninstall Mayim.
• In the cloud: Connect partner → Delete my cloud account. This deletes your Firebase account and, if you created the shared calendar or are its only member, all of its encrypted data; otherwise it removes you from it.
• You can also request deletion by email; see delete.html. We complete requests within 30 days.

Security

Data is encrypted in transit (TLS) and, for synced records, end-to-end. Access is limited by server-side security rules to the members of each shared calendar. If you remove your partner, Mayim moves your calendar to a new key; records your partner already received remain on their phone.

Children

Mayim is intended for married adults and is not directed to children.

Not a halachic ruling

Mayim's calculations are aids for personal review and do not replace a rav's guidance.

Changes and contact

We will update this page if our practices change. Questions: black29llc@gmail.com.