Pendulum Tracker -- SimuFísica: A Web-based Tool for Real-time Measurement of Oscillatory Motion

We present Pendulum Tracker, a computer vision-based application that enables real-time measurement of the oscillatory motion of a physical pendulum. Integrated into the educational platform SimuF\'isica, the system uses the OpenCV.js library and runs directly in the browser, working on computers, tablets, and smartphones. The application automatically detects the pendulum's position via the device's camera, displaying in real time the angle-versus-time graph and estimates of the oscillation period. Experimental case studies demonstrate its effectiveness in measuring the period, determining gravitational acceleration, and analyzing damped oscillations. The results show excellent agreement with theoretical predictions, confirming the system's accuracy and its applicability in educational contexts. The accessible interface and the ability to export raw data make Pendulum Tracker a versatile tool for experimental physics teaching.