Privacy policy

Account info: your name, email address, and password. Passwords are handled by Firebase Authentication (Google) — we never see or store them ourselves.

Practice activity: the questions you see, the answers you pick, whether they were right, the named mistake behind each miss, your mastery by sub-skill, and your practice-test scores. This is the data the engine runs on — without it there's nothing to diagnose.

Billing status, if you upgrade: payments run through Stripe, and card numbers go only to Stripe — we never see or store them. What we keep is your subscription state (plan, renewal date, a Stripe customer reference) so the product knows what you've paid for.

Technical basics: the standard logs any web service generates (IP address, browser type, timestamps). We don't run third-party advertising trackers.

To run the product: pick your next question, name the mistake behind a miss, decide when to step in with a lesson, and score your practice tests.

To communicate with you: account emails like verification and password resets. We don't send marketing email you didn't ask for.

To improve Tachyon: aggregate, de-identified patterns (like which questions are missed most) help us fix bad questions and calibrate difficulty.

Tachyon's coaching may use Anthropic's Claude API to help pick your next question and phrase feedback about your mistakes. When it does, the practice context needed for that decision is processed by Anthropic under their commercial terms, which do not allow using it to train their models.

Our question bank is written ahead of time — nothing you type is used to generate questions for other students.

Nobody, by default. A solo account shares nothing with anyone.

If your account is linked to a tutor, that tutor can see your practice activity — sessions, mastery, named mistakes, and assigned-test results — so they can plan your tutoring. If you want a tutor unlinked from your account, email us and we'll do it.

We don't sell your data, we don't share it with advertisers, and we only disclose it if the law requires us to.

Our infrastructure runs on Google Firebase (authentication and database), AI coaching uses Anthropic's API as described above, and payments are processed by Stripe. Those providers process data on our behalf; they don't get to use it for themselves.

Most SAT students are minors, and Tachyon is built with that in mind: no ads, no data sales, no public profiles.

You must be at least 13 to create an account. If you're under 18, you need a parent or guardian's permission — signup asks you to confirm both.

Parents and guardians: email us to review or delete your student's data.

Data is stored in Google Firebase (Firestore) and protected by Google Cloud's security infrastructure. Access to production data is limited to the people who run Tachyon.

Email verification is required on every new account before the product unlocks — it keeps your account recoverable and confirms the address is really yours.

You can ask us for a copy of your data, ask us to correct it, or ask us to delete your account and everything in it. Email us and we'll handle it — deletion is permanent and includes your practice history.

You can stop using Tachyon at any time. If you're on a paid plan, you can cancel from the billing page — access runs through the period you've already paid for.

If we change this policy in a way that matters, we'll say so on this page and update the date below. We won't quietly weaken it.