Privacy Policy

CalcTower is a collection of free online calculators. The calculators run entirely inside your browser. The numbers you type into a calculator are not sent to our servers, and we do not store them.

We do not use third-party analytics, advertising networks, or tracking pixels on this site.

Every calculator on CalcTower performs its calculation locally in your browser using JavaScript that is part of the page. Values you enter — such as amounts, dates, measurements, or grades — are processed on your device and are not transmitted to CalcTower or to any third party.

Because calculations happen locally, results also remain on your device. Closing or refreshing the page discards them.

For completeness: loading a calculator or blog page does make an ordinary request to CalcTower’s own server to fetch that page’s descriptive content, in the same way loading any web page does. Those requests identify the page being viewed, never the values you enter into a calculator.

CalcTower uses your browser’s local storage to remember a small number of preferences. This data stays on your device and is not transmitted to us:

• calctower_theme — whether you prefer the light or dark appearance.
• calctower_favorite_tools — calculators you have marked as favourites.
• calctower_recent_tools — calculators you have recently opened, used to show recent items.

You can clear this at any time using your browser’s “clear site data” or equivalent setting. Clearing it only resets these preferences.

CalcTower does not set cookies for ordinary visitors browsing the calculators. A single cookie, calctower_session, is set only when an administrator signs in to the site’s private administration area. It is an HttpOnly session cookie used to keep that administrator signed in, and it is not used for advertising or cross-site tracking.

See the Cookie Policy for more detail.

CalcTower does not load Google Analytics, Google Tag Manager, Meta Pixel, or any comparable third-party analytics or advertising script. There are no advertising networks on this site.

The site contains a small internal usage counter that records events such as “a calculator was opened” in the browser’s memory for the duration of your visit. This data is not written to disk, not associated with you, and not transmitted anywhere; it is discarded when you close the page.

The private administration area, which is used to manage the site’s content, records an audit trail of administrator actions. Those records can include the administrator’s account email, IP address, and browser user-agent string. This applies to signed-in administrators only, not to ordinary visitors using the calculators.

Like most websites, the hosting infrastructure that serves CalcTower may keep standard server request logs. to be confirmed

As the site is currently built, those audit records are kept indefinitely: the application has no routine that deletes or ages them out, so they persist until someone removes them manually. We would rather state that plainly than imply a retention limit that the software does not actually enforce. to be confirmed

Administrator sign-in sessions carry an expiry time and stop working once it passes. The stored record of an expired session is removed the next time that session is presented, and every expired session record is also deleted whenever the server starts. There is no other scheduled clean-up.

Because so little information exists, the ways it can be used are correspondingly narrow:

• Preferences stored in your browser are used only to restore your chosen appearance, your favourites list, and your recently used calculators when you return.
• The in-memory usage counter is used only to support features during your visit and is discarded when the page closes.
• Administrator audit records are used only for security and accountability within the private administration area — to show who changed what, and to detect failed or unauthorised sign-in attempts.

CalcTower does not use information to build advertising profiles, to track you across other websites, or to make automated decisions about you.

The main protection here is structural: because calculator inputs never leave your browser and no visitor accounts exist, there is no store of visitor personal data that could be exposed.

For the private administration area, the application implements:

• Password hashing with a salted key-derivation function (scrypt) rather than storing passwords directly.
• HttpOnly session cookies, marked Secure in production, so session tokens are not readable by page scripts.
• CSRF verification on state-changing administrative requests.
• Throttling of repeated failed sign-in attempts.
• X-Content-Type-Options and X-Frame-Options response headers.

No system can be guaranteed completely secure, and we do not claim otherwise. These are the measures the application actually implements, not a guarantee against every possible risk.

Based on how this site is currently built, CalcTower does not:

• Provide public user accounts, sign-up, or login.
• Operate a contact form, newsletter, or mailing-list sign-up.
• Accept file uploads from visitors.
• Process payments, subscriptions, or billing of any kind.
• Sell, rent, or trade personal information.

Fonts and interface assets are served from CalcTower’s own domain rather than a third-party content delivery network. Browsing the calculators, categories, and legal pages therefore does not cause your browser to contact any outside service.

There is one exception. Some articles in the blog use a header image hosted on Unsplash (images.unsplash.com). Those same images are also used as thumbnails on the blog listing page, so simply browsing the list loads them — you do not have to open an article. In either case your browser requests the image directly from Unsplash, which means Unsplash can see your IP address, your browser’s user-agent, and the page you were viewing. This applies only to blog pages carrying such an image — no calculator, category, or legal page loads a third-party image. to be confirmed

The administration area can optionally be connected to a Google account so the site owner can review their own Search Console and Analytics property data. This is a connection made by the site owner to their own Google account. It does not place any tracking code on this website and does not involve visitor data collected by CalcTower.

CalcTower is a general-purpose calculator website and does not knowingly collect personal information from anyone, including children. to be confirmed

Because CalcTower does not maintain visitor accounts or store the values you enter into calculators, there is generally no personal profile for us to access, correct, or delete. Preferences stored in your browser are under your control and can be cleared by you at any time.

to be confirmed

We may update this policy if the site’s functionality changes. When we do, the effective date above will be updated.

Questions about this policy can be sent to us via the Contact page.