Privacy Policy

There are no accounts, no logins, and no personal details collected

Every calculator on this site takes only numeric or category inputs relevant to the calculation itself — a deposit amount, an interest rate, an age, a number of years. Nothing asks for your name, email address, phone number, or any other identifying detail, and there is no sign-up or login anywhere on the site.

What's stored only in your own browser

A few features use your browser's own local storage — none of this data is transmitted anywhere as part of these specific features:

Your recently used calculators (shown on the calculators hub page) is kept in your browser's localStorage and persists until you clear your browser data.

Your dark/light mode choice, if you use the toggle, is kept in localStorage under the key e309-theme — just the word "dark" or "light", nothing else.

A per-tab session identifier is kept in sessionStorage (cleared when you close the tab) — a randomly generated ID with no connection to your identity, used only to recognize "this is the same visitor" for the two features below within a single browsing session.

If your browser supports it, a small number of static files (the site's stylesheet, scripts, and icons — never a calculator page or a calculation result) are cached by a service worker so the page loads instantly on a repeat visit. Calculator pages themselves are deliberately never cached this way, so you always see current figures rather than a stale result from an earlier visit.

What's sent to the server, and what happens to it

"What people are doing" and "trending calculators" — when you run a calculation or open a calculator, the calculator name and (for calculations) the input values you used are sent to the server, tagged with the random session identifier above, so other visitors can see real, recent activity on that page. This is held only in server memory, is automatically capped (a maximum of 10 recent entries per calculator, 50 site-wide), and is entirely cleared every time the server restarts — nothing here is ever written to a database or disk. Calculators dealing with more sensitive figures (income tax, HRA, gratuity, deferred annuity, Atal Pension Yojana, retirement withdrawal and corpus planning, and the FD-vs-mutual-fund comparison) are excluded from this feature entirely.

"Something look wrong?" feedback — if you submit feedback on a calculator, the calculator name, the input values you had entered, the page you were on, and your message are saved so the figures can actually be checked and reproduced. Unlike the activity feed above, feedback is saved permanently (to a plain file, not a database) and is visible only to the site administrator, never displayed publicly. Please don't include personal details in a feedback message — it isn't needed to investigate a calculation, and anything you type is kept as-is.

IP addresses

Your IP address is read only to prevent abuse — a simple rate limit (for example, no more than 5 feedback submissions per minute from the same address) stops a script from flooding these features with junk. It is held in server memory only for this purpose and is never logged, stored, or written anywhere.

Third-party services

This site loads its typeface from Google Fonts (fonts.googleapis.com / fonts.gstatic.com), which involves your browser making a request to Google's servers, governed by Google's privacy policy.

The currency converter's exchange rates come from Frankfurter, a free exchange-rate data provider. This is a server-side request our own server makes periodically to refresh rates for everyone — your browser never contacts Frankfurter directly, and no input you enter is ever sent to them.

If enabled by the site (not on by default), this site may also use Google Analytics for aggregate traffic statistics and Google AdSense to show ads. Both are Google services with their own data practices, separate from anything described above — see Google's privacy policy and, for ad personalization choices, Google Ads Settings.

Embedded calculators

Calculators embedded on other websites (see the embedding guide) load directly from e309.in inside an iframe — the same handling described above applies to any calculation made inside an embedded widget, regardless of which site it's embedded on.

Cookies

This site does not set any cookies of its own. Any cookies you see are set by the third-party services above, if enabled, and are governed by their own policies, not this site's.

Questions

For any question about this policy or how your information is handled, write to calculator@e309.in.