Subprocessors

Always

This list was last updated on October 29, 2026.

• Anthropic, PBC (United States): runs the AI models for tutoring, checks and grading. Receives the parts of your material a step needs, what you said, wrote, drew or sent in the session, the hidden answer key, and the study details on your profile that help it tailor the lesson (such as your school level, year or grade, majors, program, the tests you are preparing for, interests and goals, and, when memory is on, a short learner profile). It never receives your name or email address. Does not train on this data. Deletes it within 30 days, except content flagged by its safety systems, which it may keep for up to 2 years.
• Supabase, Inc. (United States): database and sign-in, including the emails that carry your sign-in codes. Holds your account email and ID, sign-in sessions, synced study data, answer keys, usage counts, product events, ratings, feedback notes and the record of what you agreed to. Uses your email address to send your sign-in codes. Kept for the periods in the Privacy Policy. Backups are kept 7 days.
• Vercel Inc. (United States, and its edge network): hosts the website and app, runs our server code and, on the website's front page only, counts visits, scrolling and button presses without cookies (Vercel Web Analytics). Processes request data such as IP address, country and time. For the front-page counts it receives the page, where you came from, your country and the kind of browser, with no cookie and no way to tell who you are. Our server code may run in the edge location nearest to you, which can be outside the United States when you travel. Keeps request logs for a short period for security and debugging.
• Resend, Inc. (United States): sends our account emails other than sign-in codes, such as subscription confirmations and notices that our terms changed. Receives your email address and the message. Keeps delivery logs for a limited time under its own policy, and does not use them for anything else.
• Cloudflare, Inc. (Turnstile) (United States): the human check before a sign-in code is sent. Receives browser signals and your IP address for that check, from your browser and from our server.
• Our team's chat (Slack or Discord) (United States): tells our team when something needs a person, such as a student saying they are under the age limit, the daily AI spending cap being reached, or a school's deletion request coming due. Receives only a short alert with no name, email address, account ID or words from anyone's material or sessions. A payment alert may include the subscription's reference number at Stripe, so our team can find it there. Keeps the alert in our team's chat history.

Only in some cases

• Stripe, Inc. (United States): payments, only if you subscribe to Pro. Receives your payment details directly from you on its own pages; we never see your card number. From us it receives your account email and account ID, so the subscription is tied to your account. Keeps payment records as financial law requires.
• Soniox, Inc. (United States): speech to text, only if you use the microphone. Receives your voice for the time you hold the talk button, sent straight from your browser. It turns the speech into text. Its real-time service, the only one we use, does not store the audio, and by default Soniox does not use customer audio to train its models. We never keep the audio ourselves, and we do not create voiceprints.
• Speechify, Inc. (Simba text-to-speech) (United States): reads the tutor's reply aloud in the main tutor voice, only if you turn spoken replies on. Receives the words of the tutor's reply, sent from our server. Before sending, our server puts "you" in place of the name and nickname on your profile and takes out email addresses, phone numbers and links; the rest of the reply is sent as written. Speechify states that it does not train its models on customer data. We have asked it to confirm in writing how long it keeps the text and audio, and will update this page when it answers. We do not keep the audio it makes for you.
• DeepInfra, Inc. (Chatterbox Turbo and Kokoro text-to-speech) (United States): reads the tutor's reply aloud in Heart or Bella, or when the main voice's hours are used, only if you turn spoken replies on. Receives the words of the tutor's reply, sent from our server. Before sending, our server puts "you" in place of the name and nickname on your profile and takes out email addresses, phone numbers and links; the rest of the reply is sent as written. Does not store the text we send or the audio it makes, does not log their content, and does not train on them.

What they do not get

No data brokers, session-recording tools or chat-widget companies receive Sancy AI data. Vercel, which already hosts Sancy AI, also counts visits to the website's front page, without cookies. Meta and TikTok are not service providers: if you came from one of their ads, they receive only the ad report described in the Privacy Policy.