MAL-Sync is described as 'powerful extension and userscript, which enables automatic episode tracking between MyAnimeList/Anilist/Kitsu and multiple anime streaming website'. There are four alternatives to MAL-Sync for a variety of platforms, including Windows, Hummingbird.me, MyAnimeList.net, Netflix and VRV. The best alternative is Taiga, which is both free and Open Source. Other great apps like MAL-Sync are anitrack (Free, Open Source), MAL Updater (Free) and Biyori - Anime Management (Free, Open Source).
An anime 'scrobbler', auto-updates anime on your list at MyAnimeList.net when you watch it on your computer. Includes various plugins, including one which downloads new episodes of series you are watching when they become available, via torrents.