Managify - Create & organize all your documents in a single platform.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Sismics Docs - Lightweight full-featured document management system 📁
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.
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.