I'm particular about how I like my desktop windows to appear. I don't like to fully maximize them because I want to see a little bit of the beautiful mountain, desert, or forest scene behind them. I found myself manually expanding them, but that's cumbersome. I run so many apps on so many VMs and I frequently switch monitors. It was time consuming. With Window Expander, I just have to click on the tray icon, select the "Resize Windows" menu item, and it takes care of everything.
It's currently available for Windows and Mac and it's free. There's no signup or paid features or anything. I also have a Linux version for private use. I haven't packaged it for public consumption yet, but if you want to see it, let me know.