Privacy policy

Without an account

Without an account, FormulaDojo uses your browser’s local storage (localStorage) to remember your exercise progress and your preferred argument separator. This data stays on your device.

Lesson 1 needs no account.

Accounts and sign-in

Accounts are optional. Lesson 2, First formulas, needs a free account. There are no passwords. You can sign in in two ways:

With a sign-in link. We email you a one-time link, valid for 15 minutes.

With “Continue with Google”. Google sends us your Google account’s email address, name and profile picture URL.

What we store with your account

Your name and email address, and your profile picture URL if you signed in with Google.

Whether you appear on the weekly leaderboard. Your plan, and whether you joined the Premium waitlist before Premium opened.

If you buy Premium: your Stripe customer ID, the plan you chose, your subscription ID, when your paid period renews or ends, and whether you cancelled. Your card details never reach FormulaDojo.

Every exercise you solve and when you solved it. We use this for your points, your streak and the leaderboard.

If you set one, the name you want on your certificate, and the certificate issued when you finish the course: its ID, the name on it (your account name unless you set another), the issue date and the number of lessons and exercises completed.

Your active sessions, with the IP address and browser user agent recorded by our sign-in system.

When you sign in, the progress saved on your device is copied to your account once.

Certificates

Your certificate has a public page that anyone with its link can open. The link contains a random ID that can’t be guessed. The page shows the name on your certificate, the issue date and what you completed, never your email address.

Certificate pages are marked so that search engines don’t list them. If you change the name in Settings, your certificate shows the new name.

Weekly leaderboard

The weekly leaderboard is public. It shows your first name, the initial of your last name and your points, never your email address. You appear on it by default, and you can turn this off in Settings.

If you leave a review, we store your rating and your comment, and we may publish the review: it shows your comment with your first name and last initial, never your email address. Only 5-star reviews are shown. Deleting your account deletes your review.

Where your data is kept

The site and its database (Cloudflare D1) are hosted on Cloudflare.

Sign-in emails are sent through Resend, an email delivery provider, which receives your email address and the message.

Payments are handled by Stripe. Stripe receives your email address, your card details and, for sales tax, your billing address, and keeps invoices as tax law requires. Stripe’s checkout page is governed by Stripe’s privacy policy.

Cookies, analytics and ads

When you sign in, the site sets one strictly necessary session cookie to keep you signed in. Without an account, no cookie is set.

There are no analytics, no tracking tools, no ads and no third-party cookies. Google’s own sign-in page is governed by Google’s privacy policy.

Formulas and fonts

Formulas you type are calculated in your browser.

Fonts are self-hosted: they load from this site, not from a third-party font service.

Downloading and deleting your data

You can download all your account data as a JSON file in Settings, with “Download my data”.

You can delete your account in Settings. This permanently deletes your account, your sessions, your progress and your certificate, whose link then stops working.

If you have Premium, deleting your account also closes your Stripe customer account, which cancels any subscription. Stripe keeps past invoices as tax law requires.

You can also write to us at hello@formuladojo.com.

To erase what is stored on your device, clear this site’s data in your browser settings.

Changes to this policy

If what we store or how we use it changes, we will update this page and its date.

Contact

Questions about your privacy? Write to hello@formuladojo.com.