Quiet PercentSplit Panel от Harma

Quiet PercentSplit Panel adds a minimal popup to the Firefox toolbar that helps users calculate a percentage from a Part and a Total value.

The extension runs fully offline and does not request any browser permissions.
It does not collect, store, or transmit any user data, and it does not interact with websites or browsing activity.

All functionality is bundled locally inside the add-on package, making it lightweight, privacy-friendly, and easy to review.