Effective: September 25, 2026
If you create an account: a username, your email address, your age, and a password. The password is never stored in plain text. It is hashed with a salted, industry-standard algorithm before it reaches our database.
When you use the board: your handwriting is read to recognize your equations, and a picture of the board may be sent with a Hint, Check, or chat question. We also receive the questions you ask the AI tutor, any problem you type, and any image, PDF, or Word file you choose to attach. A PDF or Word file is read on our server only to copy out its text. The file itself is not kept.
If you're signed in: we keep a history of your checked work (the recognized equation text, whether it was correct, and the tutor's feedback) and your daily challenges, so the app can track your progress and point out recurring patterns. If you write what specifically improved, we save that sentence with your account, along with the counts of problems finished, hints, sign-ins, and fixes after hints at that moment. It is deleted when you delete your account. We also keep a small amount of session context so a later visit can pick up where you left off: your chosen course level, the last problem you typed, and short summaries of your most recent checks (up to 20). This context never includes handwriting, images, chat, or your password. Math Chat conversations are not saved to your account.
Class plans (optional): you can save a school, teacher, class, syllabus, schedule, and assignments. This is tied to your account and not shown to other students. School names may be suggested to other students so the same school is not stored twice, but your classes, syllabus, schedule, and assignments stay private to you.
Exam Prep (optional): if you add an upcoming exam, we save what you enter about it: its name, class, date, length, number of questions, question types, calculator and formula-sheet rules, topics, and notes. Its question plan and readiness are worked out from the check history above each time you open it. Exam Prep does not keep a separate profile of you. When you take a mock exam or a review session, we also keep the questions written for it (with their answer keys), which questions you flagged, whether each one has work on it, and the time you spend on each question. When you submit a mock exam, a picture of your work on each question is sent to the tutor model to read and grade it; the pictures are not kept. We keep what was read from your work, the score and feedback for each question, and add each graded question to your check history above, so your patterns, weak areas, and later practice can use it. Handwriting from a review session is kept only in your browser. Questions you save or add to review are kept with your account. If you add class materials to an exam (a study guide, past quiz, notes, and so on), we read the file's text once to make a short summary: which words it uses often, up to 8 example questions copied from it, and notes on its terms and notation. We keep that summary and a fingerprint of the file so the same file isn't read twice; the file and its full text are not kept. Deleting the exam or your account removes all of it.
Raw handwriting for training (optional): we only save the actual pen-stroke coordinates of your writing to train recognition if you opt in (see the Terms of Service). It's off by default. Ordinary board sessions, the guest demo, and the small session context above do not store raw handwriting.
Homework Session (signed-in only): this mode is separate. Before it starts you must be signed in and accept the current Terms of Service, this Privacy Policy, and a specific consent to store your handwriting for that homework session. That consent is required, because resume, moving between problems, and PDF export depend on keeping the written work. For each problem we store on our server the assignment text and any assignment image you added, the raw pen strokes, the board state, recognized math when we have it, undo history when it fits, and a version with a timestamp. We also record when you accepted each policy and which version you accepted. This stored handwriting is not training data. It is not copied into the optional training set, and it is not written into the general session context used by other board visits. If you discard the session, we delete that assignment's text, images, handwriting, and session record. Generalized learning patterns already saved from checks (recognized equations and progress) stay only when your existing account choices cover them. Closing the tab does not discard the session.
Student testing sessions open only from a testing link (?testing=1). The
regular site opens the sign-in page. A testing session is separate from accounts. It saves the first name you type, whether you accepted the
terms and the optional handwriting box, your browser type and screen size, and a
recording of the session: your writing (simplified pen strokes), text and shapes you
add, checks and AI replies, chat, button presses, comments, and a note about what
specifically improved if you write one. The writing is recorded
in every testing session so the session can be reviewed. It is used to train
handwriting recognition only if you tick the optional handwriting box. Testing
recordings are reviewed by the Calcebra team and are not added to an account.
So that a refresh or a new tab puts you back where you were, a testing session also keeps a working copy of your board on our server: your pen strokes at full detail, the problem text or photo you added, your topic, your comment, and the chat. It is stored with the rest of the testing session and is not used to train handwriting recognition unless you tick the optional handwriting box.
A study link from Prolific opens the same kind of session without asking for your name. It saves your Prolific participant ID, study ID, and session ID with the session so your study work and completion can be matched to your Prolific submission. Those IDs are not shown on the page.
Voice Mode starts only when you turn it on. Your browser's speech service may process microphone audio to transcribe your words and speak replies. Calcebra sends the transcript, recent Math Chat messages, and a fresh image of the visible board to its AI tutor for each question. Calcebra does not store audio recordings. Turning Voice Mode off stops recognition and playback.
Calcebra is currently open to students age 13 and up only. We don't yet have a parental-consent process that meets the Children's Online Privacy Protection Act (COPPA), so account creation is blocked for anyone who enters an age under 13, and testing sessions require confirming you are 13 or older. We don't knowingly collect personal information from children under 13. If we learn that we have, we'll delete it. Contact us if you believe a child under 13 has used Calcebra.
We also keep aggregate daily counts, such as how many demos were started, accounts created, checks requested, challenges completed, tutor replies marked helpful, and how often a playful tutor reaction was shown or dismissed. These counters do not contain usernames, email addresses, IP addresses, questions, handwriting, images, or other user-level records.
Calcebra doesn't use advertising or tracking cookies. It uses your browser's own storage (localStorage and sessionStorage) for things the app needs: your sign-in token, course level, theme, voice and keyboard-shortcut settings, a board autosave, whether you've seen the tour, today's local progress count, and a small tone memory (how often each kind of mistake has come up recently) so the tutor's reactions can change. Testing sessions keep their session ID and panel position in sessionStorage, which clears when the tab closes. You can clear all of this at any time in your browser settings.
We don't sell your data, and we don't share it for advertising. A few service providers process it to make Calcebra work:
We may also disclose information if the law requires it, or to protect the safety of users or the service.
We keep your account data for as long as your account exists. You can permanently delete your own account and all of its data (including saved handwriting training data, Homework Session handwriting, check history, session context, and class plans) at any time from the Account panel. Click your name in the app; you don't need to contact us. If you opted into handwriting training data, you can turn it off anytime in Account settings. That stops new samples from being saved but doesn't delete ones already saved unless you delete your account or ask us to.
Once a day we make a backup copy of the account database and keep it in private off-site storage. Deleting your account removes your data from the live service right away, but it can remain in older backup copies until those copies are removed. We use backups only to recover from data loss, and we don't restore deleted accounts from them.
Testing-session recordings and tutor-reply reports are kept so they can be reviewed. To have a testing session or report deleted, email us with the first name you used and roughly when you tested.
Depending on where you live, you may have the right to access, correct, delete, or get a copy of your personal information, and to object to or limit some uses of it. You can delete your account yourself from the Account panel. For anything else, email us at the address below. We'll respond within a reasonable time and won't treat you differently for making a request.
Passwords and sign-in tokens are stored only as hashes. The site is served over HTTPS, backups are kept in private storage, and admin tools require a separate secret token. Like any project this size, we can't guarantee perfect security, but we take reasonable, standard precautions.
Calcebra and its service providers may store and process data in the United States and other countries where they operate.
If this policy changes in a material way, we'll update the effective date above and, where appropriate, show a notice in the app.
Questions, deletion requests, or concerns: hello@calcebra.com
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