Joplin - 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, tagged and modified either from the applications directly or from your own text editor.
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Standard Notes - A safe place for your notes, thoughts, and life's work
Morgen.so - All-in-one Calendar, Tasks & Scheduler. Morgen is the single hub for everything that revolves around time management.