Trillium is a full featured configurable and programmable self-hosted note-taking app that can be easily configured to suit the use case you’re describing, it does categories, tags, links to other topics etc.

Nope, were shiftin’ back, bby.

I started using Trilium in early 2020, with version 0.40.2. Roam had released in 2019 and was growing in popularity quickly, I heard a lot about Roam, it looked cool, so I googled for an open-source self-hosted knowledge base note taking app with similar features to Roam, like notes arranged in a knowledge graph, and a backlinks explorer for each note. The only one that was available then was trilium. Looks like you’re right, the development of trilium was started in 2017, before Roam existed. This is a great interview with the creator, answers a lot of the questions I had. https://console.substack.com/p/console-169

Obsidian didn’t come out until a few months later (and remained under the radar until 2021), all my colleagues and friends use Obsidian now, but I prefer trilium. I had never heard of logseq before I read this thread. Just a quick glance, I see the first 0.1.0 version logseq was in April 2021, just before the first obsidian release.

Trillium was originally created to be an open source replacement for Roam Research. Trilium came out in 2017, and had Roam-like features before Roam even existed. It’s similarities to Obsidian are purely coincidental, probably because Obsidian is designed to be a cross between Roam and Evernote.