Privacy Policy

For the fosterapps.com website, web calculators and Foster Tools Pro. Last updated October 27, 2026. Each app has its own privacy policy on its app page.

Analytics without tracking cookies

We count how the calculators are used so we can improve them: page views, whether a calculator was used, which features were tapped, which site referred you (for example a search engine), your country (from your IP address) and whether you're on a phone or computer. We don't use analytics cookies, advertising trackers or third-party analytics. A visit is counted with a code derived from the day, your IP address and your browser type. It changes every day, so it can't be used to follow you over time, and we don't store your IP address.

Sometimes we test two versions of the Pro offer, such as different prices. Your browser keeps one random number (0 to 99) in local storage so you see the same version on every visit. It isn't linked to you, and it's only used to choose that version.

What you type into calculators

Calculator inputs and results stay in your browser. We don't send or store them.

Foster Tools Pro

Payments are handled by Stripe. We never see or store your card number. Stripe shares your email, billing country and subscription status with us. See Stripe's privacy policy.
Your email is used to keep track of your subscription, send sign-in links when you ask for one, and contact you about your subscription. We don't send marketing email or share your email with anyone else.
Sign-in cookie: when you buy Pro or sign in, we set one cookie that keeps you signed in on that browser. It's needed for Pro to work and isn't used for anything else.

Service providers

The site runs on Cloudflare (hosting, security and email delivery) and Stripe (payments). They process data only to provide those services.

Keeping and deleting data

Usage counts are kept to see trends over time. Subscription records are kept as long as you're a customer and as long as tax and accounting law requires afterwards. To access or delete your data, email support@fosterapps.com.

Contact

Foster Apps LLC, support@fosterapps.com.