Privacy Notice

Last updated October 20, 2026

Who is responsible

Matthew Isaac Rosenberg runs Study Stereo and is the data controller for the personal data described here. Contact: matt@studystereo.com.

What we collect and why

Account details (email address, name and profile picture from Google if you use it): to create your account and sign you in. Legal basis: contract.
Study data (goals, timer sessions, streaks, flashcards, stories, plans and takeaways): to save your progress across devices. Legal basis: contract.
AI coach prompts: sent to an AI provider to generate your answer; not used to train models; counted to apply daily limits. Legal basis: contract.
Feedback and support messages: to answer you and improve Study Stereo. Legal basis: legitimate interests.
Referral activity (who invited whom): to grant referral rewards. Legal basis: contract.
Technical data (IP address, device and browser type, error logs, anonymous "online now" counts): to keep the service secure and working and to prevent abuse. Legal basis: legitimate interests.
Purchase status (your plan and its renewal date): to unlock Plus. Card details are collected by Paddle, not by us.

Who we share it with

Service providers who host and run the app for us: hosting, database and sign-in, AI processing, and email delivery.
Paddle, our Merchant of Record, for selling Plus, subscription management, payments, tax compliance and invoicing.
Professional advisers such as lawyers and accountants, where needed.
Authorities, where the law requires it.

We don't sell your personal data. Some providers may process data outside your country; where they do, we rely on safeguards such as standard contractual clauses.

Emails

We send account emails (sign-in links, a welcome email, session receipts and purchase receipts). Every email has an unsubscribe link.

How long we keep it

We keep your data while your account is active. If you ask us to delete your account, we delete or anonymise your data within 30 days, except records we must keep by law (for example, purchase records).

Your rights

Depending on where you live, you can ask to access, correct, delete or export your data, object to or restrict how we use it, and withdraw consent. Email matt@studystereo.com and we'll respond within one month. You can also complain to your local data protection authority.

Security

We use encryption in transit, access controls and per-user data isolation to protect your data.

Cookies and local storage

We use only essential browser storage: to keep you signed in and to save your settings and progress on your device. We don't use advertising or third-party tracking cookies.

Changes

We'll update this notice when our practices change and show the new date at the top.