If you're having trouble using Falstad on a Mac, it might be due to Java compatibility issues. Make sure Java is installed and updated to the latest version. Sometimes, browser settings block Java-based apps; try enabling it or switching browsers. If you're using macOS Ventura or newer, security settings might block the app—allow it in "System Preferences > Security & Privacy." If the problem persists, consider using an online version or downloading a standalone simulator.