Privacy policy

Effective date: [EFFECTIVE DATE]

Who runs Syntactical

Syntactical is run by [OWNER NAME]. Questions about this policy or your data: [CONTACT EMAIL].

What we collect

  • Your email address, only if you sign in. It is used to send you one-time sign-in codes and to identify your account. You can also set a password. We store only a salted scrypt hash of it, never the password itself. When you choose a password, our server checks it against the Have I Been Pwned list of breached passwords by sending only the first 5 characters of the password's SHA-1 hash, so neither the password nor its full hash leaves our server.
  • If you are signed in: your answers (which question, your choice, whether it was correct, and how long it took), your daily progress and daily goal, and your timezone (a name such as America/Chicago, used to decide when your day starts). This is not your location.
  • If you are signed in and use them: the questions you type about a card in Ask, your choice on a card you got wrong when you use Explain my mistake, and your weekly study note. A question or that choice is sent with the card to Anthropic, or to OpenAI when Anthropic cannot answer, to write the answer; we do not store or log it. Your study note is stored with your account until a newer note replaces it.
  • A random user ID that we create for your account.
  • Purchase history: whether your account has Pro, on the annual or lifetime plan, and until when, and the purchase events RevenueCat sends us. We never see your card number. In the iPhone and Android apps, Apple or Google handles payment; on the website, purchases go through RevenueCat Web Billing once they open there.
  • Usage events, such as starting or finishing a round, seeing the Pro sheet, completing a purchase, or seeing or pressing a sponsored card, with details like language, difficulty, and where the card was. These go to PostHog. Location lookup is turned off. When you are signed in, events carry your random user ID, never your email. When you are not signed in, events are anonymous, and analytics writes nothing to your device.
We do not collect your name, phone number, address, contacts, photos, or precise location. Free users see sponsored cards: a card for Syntactical Pro, a sponsor we name in the card, on iPhone and Android a card from Google AdMob, and on the website a text card from EthicalAds, which sets no cookies. AdMob cards are always non-personalised. Google AdMob receives your IP address, from which it may infer an approximate location, and device information, to serve and count sponsored cards. The app never asks to track you and does not use an advertising identifier to track you. A named sponsor's card comes from our own site, so the sponsor learns nothing unless you open its link. Pro removes them. The app does not track you across other companies' apps or websites. No crash reporting service is installed.

What stays on your device

If you do not sign in, your progress and daily goal are stored only on your device. If you sign in, the app also keeps your sign-in session there: in the device keychain or keystore on iPhone and Android, and in a cookie in the browser. We store only a hash of the session token on our server.

Why we use it

  • To sign you in and run your account.
  • To sync your progress, streak, and XP across devices.
  • To answer the questions you ask about a card, to explain a mistake you ask about, and to write your weekly study note.
  • To give you Pro, and to restore it on a new install or another device.
  • To understand how the app is used so we can improve it.
  • To show sponsored cards to free users and count how often they are seen and pressed.

Who processes it for us

  • Neon: hosts the database that holds accounts, answers, progress, and purchase records.
  • Railway: hosts the server.
  • Anthropic: answers a question you ask about a card, explains your choice on a card you got wrong when you use Explain my mistake, and writes your weekly study note. It receives the card, its answer and explanation, your choice, and your question if you typed one, or a summary of your week (counts by bank and the mistakes you made), never your email or user ID.
  • OpenAI: does the same when Anthropic cannot answer, and receives the same text whenever a request is sent to it.
  • Cloudflare: hosts the website.
  • Resend: delivers the one-time sign-in email.
  • RevenueCat: manages purchases and entitlements, together with Apple and Google.
  • PostHog: product usage analytics.
  • Google AdMob: serves the non-personalised sponsored cards on iPhone and Android, and asks for consent where the law requires it.
  • EthicalAds: serves the text sponsored cards on the website, without cookies. Your browser fetches each card from EthicalAds, which sees its IP address.
  • Apple and Google: process payments in the iPhone and Android apps and keep their own purchase records.
  • RevenueCat Web Billing: handles purchases on the website, once they open there.
We do not sell your data and we do not share it with data brokers.

How long we keep it

We keep your account data until you delete your account. A sign-in session expires after 14 days without use and after 30 days in all. You can delete your account at any time; see the account deletion page.

What deleting your account removes

Deleting your account removes your email, your password hash, sessions, answers, progress, goal changes, study notes, and unused sign-in codes from our database. Records of purchases stay for accounting, with your account link removed; they hold no email or name. Signing in again with the same email starts a new, empty account.
Deleting in the app does not reach our vendors. These remain with them under their own policies: PostHog usage events tied to your random user ID, the RevenueCat customer record, Resend's record of the emails it sent, Google AdMob's records of the sponsored cards it served to your device (not tied to your account), the questions you asked about a card, the choices you sent with Explain my mistake, and the weekly summaries behind your study notes, kept by Anthropic, and by OpenAI when a request was sent to it, under their API data-retention terms (they carry no email or user ID), and the purchase records of Apple and Google. To ask a vendor to remove its copy, write to [CONTACT EMAIL].

Children

Syntactical is not directed at children under 13, and we do not knowingly collect their data. If you believe a child has given us data, write to [CONTACT EMAIL] and we will delete it.

Changes and contact

If this policy changes, we will update the effective date above. Contact: [OWNER NAME], [CONTACT EMAIL].