Privacy

What happens to a reading you type in

The calculator runs entirely on your device. The two numbers exist in your browser’s memory while the page is open and are gone when you close the tab. They are not put in the web address, not stored in a cookie, not written to a log, and not included in any error report.

If you use the log, your saved readings are stored in this browser on this device only, using your browser’s own local storage. They are never sent to us and we cannot see them. Clearing your browser data, using a different device, or private browsing will lose them.

Don’t take our word for it

A privacy policy is a claim. Here are the two mechanisms that make this one checkable.

One. This site sends a Content-Security-Policy header that includes connect-src 'none' and form-action 'none'. That instructs your browser to block every outbound network request this page could possibly make — including background requests, form submissions and tracking beacons — whether or not our code tries to make one. Open your browser’s developer tools, watch the network tab, and enter a reading: nothing is requested. The image policy is restricted for the same reason, because loading a remote image is the oldest way to smuggle a value off a page.

Two. Every change to this site is checked automatically for outbound calls in any code that touches a reading. A change that introduces one fails before it can be published.

What we do not collect

• No account, sign-in, name, date of birth, phone number or email address. There is no field anywhere on this site that asks for any of them.
• No blood-pressure readings, ever, in any form.
• No advertising, no pixels, no tag manager, no session recording, no A/B testing tool and no chat widget — on any page.
• No fonts, scripts or images loaded from anyone else’s server. Everything the page needs comes from this site.

Cookies

One, and only if you use the light/dark toggle. It holds the word “light” or “dark” so the page does not flash the wrong colours when you come back. It contains nothing else, and no reading value can reach it.

No devices, no health apps

bpmeter will not connect to a Bluetooth cuff, a smartwatch, Apple Health, Google Fit, Health Connect or any other health service, in this version or a later one. Readings are typed in by hand and that is the only way in. The site also tells your browser to make Bluetooth unavailable to it entirely, so the capability is absent rather than merely unused.

If this ever changes

If any third-party service is ever added to a page on this site, this page will be updated in the same change that adds it, and it will still never appear on a page where a reading is entered or displayed.