Ruler Tool is a professional measurement app with ​high-precision image measuring​ (0.1cm-5m, metric/imperial), drag-and-drop virtual ruler with auto-calibration. Includes ​spirit level (angle), protractor (0-180°), plumb line (verticality)​​ with deviation alerts. Auto-saves measurement history (timestamp/tags) and exports ​scaled screenshots as PDF reports. Extra features: ​unit converter, ​screen ruler calibrator​ (UI design), ​compass, ​sound level meter, and ​speed test.