Obsidian

It's free for personal use, full pricing information available here.

Obsidian is a powerful knowledge base that works on top of a local folder of plain text Markdown files. For portability, Obsidian supports CommonMark and GitHub Flavored Markdown (GFM).

Links as First-Class Citizens We want your second brain to work like a real brain, so Obsidian encourages you to make connections between your notes. Simply type [[ and Obsidian will auto-complete the link. With connections in place, you can navigate your notes and get inspiration with backlinks and graph view.

The Note Multiplexer Obsidian is great if you have large screens and atomic short notes. Panes in Obsidian can be split infinitely and resized, and they make cross-referencing multiple notes a breeze. Panes can be pinned to keep its content or linked together so they can show different views of the same note. Combine panes to set up your powerful workspaces.

Build Your Custom Obsidian With dozens of actively-developed plugins, you can build your own note-taking toolkit like a Lego set.