Opportunity Cost Calculator stores everything on your device only. Your purchase amounts, settings, and saved projections live in your browser’s local storage. Nothing is uploaded to any servers or shared with third parties.
You can install this app and use it without an internet connection after the first visit. Calculations run entirely on your device.
I do not collect analytics, telemetry, or usage data. No account is required.
To erase all stored data at any time, use the Reset All Data button. That permanently clears your settings and saved projections from this device.