George Moody is the architect and engineering director of PhysioNet, and the author of WAVE, the WFDB library, and many of the WFDB applications. PhysioNet (http://physionet.org), established in 1999 as the NIH-sponsored Research Resource for Complex Physiologic Signals, was the first, and remains the world’s largest, most comprehensive and most widely used repository of time-varying physiologic signals. Its software collection, PhysioToolkit, supports exploration and quantitative analyses of PhysioBank and similar data with a wide range of well-documented, rigorously tested open-source software that can be run on any platform. By providing free access to its unique and wide-ranging data and software collections, PhysioNet enables studies that lead to an average of 80 scholarly publications per month (well over 5000 studies since 1999) by academic, clinical, and industry-affiliated researchers worldwide.