Obsidian is a powerful knowledge base that works on top of a local folder of plain text Markdown files. The human brain is non-linear: we jump from idea to idea, all the time. Your second brain should work the same. In Obsidian, making and following connections is frictionless. Tend to your notes like a gardener; at the end of the day, sit back and marvel at your own knowledge graph.
Obsidian is built to be extensible. With 22 core plugins and counting, set up your own toolkit and get running in minutes. You'll even be able to install third party plugins or build your own.