Privacy policy

Who we are

Cahier is run by [Legal owner: the parent's name or the LLC's name, to be filled in] ("we", "us"). A high-school student built it, and an adult is the legal owner and is responsible for it.

Questions or requests: support@studycahier.com, or use the form on the support page. Postal address: [to be added].

Who Cahier is for

Cahier is for people aged 13 and up. When you first open it, we ask for your birth month and year. If you are under 13, Cahier stops and stores nothing about you except a note in your browser that the check was done. If we learn that someone under 13 has an account, we delete it.

We store only whether you are 13–17 or 18+, never your birth date.

What we collect

• Your account: your email address, and your name if you sign in with Google. Your age group (13–17 or 18+).
• Handouts you upload: the PDFs and photos of class sheets you give us, and the note you type with them. These can contain other people's names, a teacher's notes, or faces in a photo, so please crop those out when you can.
• What Cahier builds: the study units, activities and questions made from your handouts.
• How you practice (attempt logs): for each answer, which question and skill it was, whether it was right, any hint or retry, how long it took and when. If you type a wrong answer, we keep what you typed (up to 80 characters) so Cahier can tell what kind of mistake it was. A teacher never sees what you typed.
• Settings: language, course, test dates, dark mode and similar choices.
• Classes: class codes you join and the classes you belong to.
• Reports: when you report a question, the reason and the short note you write.
• Payments (later): whether a plan is paid and when it renews. The card details go to Lemon Squeezy, which sells the plans for us; we never see them.
• Technical logs: error reports (which page broke, with no answers or page text) and basic server logs. On our public pages we count visits without cookies. We use no tracking cookies and no advertising tools anywhere.

Why we use it

• To build your study units from your handouts.
• To grade your answers, track which skills you know and plan your next review.
• To let a teacher see results for their own class, if you join one.
• To keep Cahier safe and working: preventing abuse, fixing bugs, limiting costs.
• To improve Cahier, using counts and patterns, never by selling or sharing your data.
• To handle payments, once paid plans exist.
• For a research pilot, only if you and a parent both say yes (see below).

What we never do

• No ads, and no targeted ads.
• We never sell or rent your data.
• No AI is trained on your handouts, answers or anything else about you, by us or by our AI provider.
• We build no profile about you except what you're learning, for studying.

AI and the companies that help us

The AI that reads your handouts and writes questions is Claude, made by Anthropic. We send it the handouts and note for the unit being built, and, for sorting mistakes, a wrong answer (up to 80 characters) with no name, email or account id. Anthropic's commercial terms say it does not train its models on this data. Anthropic deletes it after a short time, but may keep content its safety systems flag for up to 2 years. More on the How we use AI page.

While Cahier is being built, the student developer also tests with Google's Gemini on their own test material. Gemini is never used for anyone else's account, and none of your data is sent to it.

These companies process data for us under contracts and may use it only to provide their service:

• Anthropic: the AI (Claude).
• Supabase: our database, sign-in and private file storage (United States).
• Cloudflare: hosting for the website and server, and our domain. Requests are handled in Cloudflare's data center nearest you; your data is stored with Supabase.
• Google: "Continue with Google" sign-in, if you choose it.
• Lemon Squeezy: the seller of the paid plans (it takes the payment, sends the receipt and handles sales tax), once paid plans exist. It is the payer's merchant of record, so its own privacy policy covers the payment details.
• Sentry: error reports, with no answers or page text.
• Resend (or Postmark): sending emails such as sign-in links.
• Plausible: cookie-free visit counts on public pages only.

Your data is stored and processed in the United States.

Who else can see your data

• Your teacher, if you join their class: your display name, your scores on the units they assigned, and which kinds of mistakes you make. Your teacher can't see what you type. Not your other units, not your handouts. Cahier's owner checks each teacher account by hand before it can make a class.
• People you share a link with can see that unit's activities after signing in. Your uploaded files are never shared.
• Nobody else, unless the law requires it (for example a valid court order), or to protect someone's safety.

How long we keep things

• Uploaded handouts: deleted 30 days after your unit is built. The activities stay.
• Typed wrong answers: the text is erased after 90 days. Whether the answer was right stays, so your progress still works.
• Data exports you download: deleted after 7 days.
• Your account and practice history: kept while you have an account. When you delete it, it goes at once; any leftovers are cleared within 30 days.
• AI cost logs: kept 13 months for billing, with no content and, after you delete your account, no link to you.
• Proof of deletion: a scrambled code (not your id or email) and the date, so we can show we deleted your account.

Your rights, and your parent's

• See your data: Account → "Download my data" gives you a file with everything we keep about you.
• Delete it: Account → "Delete my account" removes it right away.
• Fix it: change your settings in the app, or write to us.
• Parents and guardians of a student under 18 can ask to see, correct or delete their child's data. Write to support@studycahier.com. We will check that the request really comes from the parent, then answer within 30 days.
• If a school or district set Cahier up for you, requests about school records go through the school.
• Depending on where you live (for example California), you may have more rights. We will honour them. [Lawyer: add state notices.]

The research pilot

We may run a small study with a class to see whether Cahier helps people learn. It is separate and optional. A student joins only if they agree and, if under 18, a parent agrees too. Study data uses a random code instead of names or emails. You can leave at any time, and leaving or saying no changes nothing else about how Cahier works for you.

How we protect your data

• Everything travels encrypted (HTTPS) and is stored encrypted.
• Uploaded files are private. Only your account and our server can read them.
• Database rules make sure each account can read only its own data (or its class's, for a teacher).
• Only the adult owner and the developer can reach the systems, with two-factor sign-in.

If a breach ever affects your data, we will tell you (and a parent, if we have their contact) by email without delay, and as the law requires.

Changes to this policy

If we change this policy in a way that matters, we will tell you in the app or by email before the change applies. The date at the top shows the latest version.

Contact

support@studycahier.com, or the support page.