While going “low-tech” with simple text files and lightweight text editors, I have found Roam (https://roamresearch.com) very interesting. It’s a web app and was designed specifically to support zettelkasten. It simplifies the tasks of making, maintaining, and searching for tags, as well as organizing information in a graph structure, as well as general outlining functions.

It’s quite new and a little rough around the edges, but it’s surprisingly easy to use.