Tracker (Version 5.9 Beta)

Browser Support

JavaScript Tracker is compatible with Chrome, Safari and Firefox browsers on desktop computers including Chromebooks. Compatibility with browsers on mobile devices is limited at this time.


Tracker is a free video analysis and modeling tool built on the Open Source Physics (OSP) framework. It is designed to be used in education and is supported by the AAPT-ComPADRE National Science Digital Library. If you're new to Tracker, please see Help Getting Started for a step-by step beginner's guide or Getting Started with Tracker for a video tutorial before using the JavaScript version of Tracker. Additional information about Tracker is available on the main Tracker website.

Note that users can reposition the JavaScript Tracker window by dragging the title bar and that the window can be resized by dragging the lower right hand corner.

Bug Reports

Video Clip Formats and Tracker Experiments

JavaScript Tracker supports video clips in the following formats

Tracker Experiment files are special Tracker zip (e.g., *.trz files) archives that contain video clips, Tracker xml data files (e.g., *.trk files) and supplemental documents, such as PDF files. Experiment files that contain older video formats, such as *.qt or *.avi, can be loaded into Tracker but they will not display any video. Users will need to convert older formats into a supported format using a third-party program, such as Cloud Convert..

Click on the links below to test the JavaScript implementation of Tracker on your computer.

Users can download trz files or mp4 video clips to the desktop and then use the File options in the main menu to open or import them into Tracker.

Another way to Tracker Experiment files or video clips into Tracker is to drag and drop them from the desktop onto the Tracker window.

Finally, users can use the Tracker library browser to import Tracker video experiments from various digital libraries, such as the OSP Collection on the AAPT-ComPADRE library -- provided that the video clip in the *.trz file is encoded in a supported format.


The Tracker Java program was written by Doug Brown at Cabrillo College using portions of the the Open Source Physics code library developed by Wolfgang Christian at Davidson College. Tracker was later converted from Java to JavaScript by Doug Brown, Wolfgang Christian and Robert Hanson using the SwingJS system developed by Hanson and his students at St. Olaf College.