This site is not using cookies or any tracking at all.
Neither the site nor the chessrating app is commercial. It is a just for fun project because the author wants it so.
The app chessrating is not tracking users. It is not spying on you. All versions prior to V2.5 (internal Version number 15) are completely without any connectivity. From V2.5 on some anonymized data is being transferred to the server to improve the app and to make it easier to add new positions. You can disable all connectivity in the options.
Feel free to contact the author Oliver Kertesz for bug reports or feature requests via email: kertesz[æt]web(dot)de