Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
Agenda - A date-focused note taking app for both planning and documenting your projects.
Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.
Notepin - Extremely simple note-taking + blogging ✍️
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
Bear - Bear.app is a note-taking and content writing app that helps you boost productivity with its intuitive tools.