This is the first large-scale analysis of Grandmaster activity across Chess.com and Lichess from 2008 to 2025, based on years of data collection and millions of games. I explored which platform top chess players prefer and how Chess.com and Lichess have evolved over the years.<p>All data comes from my project ChessMonitor, which maintains one of the largest chess databases in the world. Feel free to check it out! :)