SwissTasks is described as 'shows due items such as notes, emails, calendar events and things to log in one list. It also supports you to achieve your goals by means of a weekly score' and is an app in the Office & Productivity category. There are more than 100 alternatives to SwissTasks for a variety of platforms, including Online / Web-based, iPhone, Android, Windows and Mac. The best alternative is Joplin, which is both free and Open Source. Other great apps like SwissTasks are Standard Notes (Freemium, Open Source), Google Keep (Free), Trello (Freemium) and Microsoft OneNote (Freemium).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.