Jackett is described as 'works as a proxy server: it translates queries from apps SonarrRadarrSickChillCouchPotato ' and is an app in the File Sharing category. There are seven alternatives to Jackett for a variety of platforms, including Linux, Windows, Mac, Self-Hosted solutions and Online / Web-based. The best alternative is Sonarr, which is both free and Open Source. Other great apps like Jackett are DuckieTV (Free, Open Source), Radarr (Free, Open Source), Ombi (Free, Open Source) and SickChill (Free, Open Source).
Ombi is a front end user facing request system. It connects with your other media managers (CouchPotato, SickRage, SickGear, Sonarr, Lidarr, and Radarr, etc) to automate user requests and adding them into your media library managers.