Launch HN: Athens Research (YC W21) – Open-Source Roam Research
A few alternatives in this space:org-roam https://www.orgroam.com/tiddlyroam https://tiddlyroam.org/Dendron https://dendron.so/Foam https://foambubble.github.io/foam/Remnote https://www.remnote.io/Obsidian https://obsidian.md/logseq https://logseq.com/Not an expert with them at all. I've never had a desire to dig into all their complexity, but some are pretty passionate about it.