Privacy
Here's the honest version: the calculators run in your browser, the numbers you type aren't sent to us, and the few things we do measure are written in plain language below. No signup, no ads.
Last updated
Your numbers stay in your browser
Osvian is a static website. There's no account system, no login, and no database holding your inputs. When you use a calculator, your browser loads a small piece of code and does the arithmetic right there on your screen. Nothing you type into a field is transmitted to us to produce the result — because there's no server doing the math.
That's a deliberate design choice, not a slogan. It keeps the site fast, it means a result still appears even if our analytics never loads, and it means the most sensitive thing on any page — your actual numbers — never leaves your device just to be calculated. When you export a result as a CSV, PDF, or printout, that file is generated in your browser too.
What we measure (and what we don't)
We use Google Analytics 4, loaded through Google's Firebase Web SDK, to understand which calculators people find useful and where the site is confusing. It's how we decide what to build next. We don't sell this data, and there are no advertising trackers on the site. Analytics is the only third-party layer here, it loads lazily after the page is usable so it can never delay a result, and if it isn't configured — or a tracker blocker stops it — it quietly does nothing and every calculator works exactly the same.
Being honest means naming what we collect, and just as importantly, what we never collect:
| Collected (aggregate, non-personal) | Never collected |
|---|---|
| Which page you viewed, your device type and browser, and a few intent signals — for example that a calculator was opened or a filter was applied. | Never: the values you type into a calculator — your salary, your weight, a blood-pressure reading, an hourly rate. No magnitudes are sent as event data. |
| A rough region (country or area), estimated from the IP address your browser sends with any web request and then discarded by Google. We never see your raw IP. | Never: your name, email, or any account identifier — there are no accounts, so there's nothing to attach a measurement to. |
| A repeat-visit count, so the same browser isn't recorded as a brand-new visitor on every page. | Never: anything you save in a tool — your blood-pressure log, your medication list, your saved quotes. Those stay on your device (see below). |
No pixels on cycle, fertility, or doctor-visit tools
Things you save are stored on your device
Some tools are useful precisely because they remember. A blood-pressure log, a medication list, or a saved invoice would be pointless if it forgot every entry on refresh. So those tools save your entries in your browser's local storage — a small box of data that lives on your device.
We want to be precise here, because it's tempting to over-promise. We do not say "we store nothing." We say this: what you save is stored on your device, and you can clear it. We can't read it, and it isn't backed up to us. The trade-off is the honest one — clear your browser data, switch devices, or use a private window, and those entries are gone, because they only ever lived where you put them.
How to clear what's saved: many log tools include a "Clear saved data" control right on the page. You can also clear everything for this site through your browser's own settings — look for "Clear site data," "Cookies and site data," or "Local storage." Clearing it removes both the analytics cookies and any tool logs in one step.
No accounts, no payments — today
Today there are no accounts. You can't sign up, you can't log in, and there's nothing to "agree" to in order to use a calculator. There are no payments and nothing to buy. That's the right starting point for tools that should just give you the answer.
We may later offer an optional account so you can sync your saved logs across devices. If we ever build that, it will be exactly that — optional — every existing tool will keep working with no account, and we'll update this page first, before any such feature ships, to explain plainly what it would store and why. We won't quietly start collecting more than we describe here.
Cookies
We don't set first-party cookies that identify you, and there are no advertising or social-tracking cookies on the site. The only cookies that may appear are the ones Google Analytics sets — and only when the analytics layer actually loads, which it doesn't on the no-analytics health pages described above, and doesn't at all when analytics isn't configured.
If you'd rather refuse them, you can block cookies for this site in your browser settings, use a content blocker, or turn on your browser's "Do Not Track" / tracking-protection setting. The calculators keep working either way, because the math never depended on analytics.
Questions
If something here is unclear, the about page explains who publishes Osvian, and the methodology page shows how each result is calculated and what it's based on. For how to read the numbers themselves, see the disclaimer — every result is an educational estimate, not professional advice.