Privacy Policy

Last updated: August 5, 2026

Hearth is a free, no-signup tool. This page explains what happens to your data when you use this site — in short, very little, because there isn't much to explain.

What we don't collect

There are no accounts and no login. The calculators on this site run entirely in your browser: whatever you type into a calculator (times, weights, dates, and so on) is used to compute a result on your device and is never sent to or stored on our servers.

Cookies

One cookie, and it only remembers a language. If you read Hearth in Hebrew or Arabic — or switch back to English — we store that choice so the next page you open comes up in the same language instead of guessing again from your browser settings.

Name:lang
What it holds: a language code — en, he, or ar. Nothing else. It is not an identifier, it is not tied to an account, and it cannot be used to recognise you.
How long: one year, unless you clear it sooner.
How it's set:SameSite=Lax and Secure, so it is sent only to this site, only over an encrypted connection, and never to anyone else's.
Who doesn't get it: search-engine crawlers, which are served every language directly and are never given a cookie.

It is a preference, not tracking: no profile, no cross-site history, no advertising use, and it is never shared. Clearing your cookies removes it and the site works exactly the same afterwards — it simply falls back to your browser's language setting. There are no other cookies on this site.

Analytics

This site may use Cloudflare Web Analytics to understand how many people visit and which pages they read. It's beacon-based and privacy-first by design: no cookies of its own, no cross-site tracking, and no persistent identifier that follows you between visits or between sites. It reports aggregate counts (page views, rough location, device type) — it does not identify you individually, and we don't combine it with anything else.

Third-party links

Some pages link out to outside sources (for example, the medical or veterinary references a calculator cites). Those sites have their own privacy practices, which this policy doesn't cover.

No sale of data

We don't sell, rent, or share visitor data, because we don't collect any in identifiable form to begin with.

Changes to this policy

If what we collect ever changes — for example, if a future feature adds a contact form or email signup — this page will be updated first, with a new "last updated" date above, before that feature ships.

Contact

A dedicated contact address for this site isn't live yet. Check back here once one is — this page will link it the same day.