• VIKI (Xerox Palo Alto Research Center)
• SkyWiki
• Microcosm (University of Southampton)
• Webspiration
• VKB
• XandauSpace

These tools could be considered spatial (hypertext) knowledge graph style tools.

• https://gra.fo/
  • https://www.youtube.com/watch?v=-3BdHoe_TkY
• https://graphcommons.com/
• http://www.eastgate.com/Tinderbox/
• https://cmap.ihmc.us/
• https://www.thebrain.com/
• http://getdiscovr.com/
• https://whimsical.co/
• https://mural.co/
• https://www.milanote.com/
• https://realtimeboard.com/
• https://www.nuclino.com/
• http://vowl.visualdataweb.org
• https://mindgraph.co/
• https://www.omnigroup.com/omnigraffle/
• https://drawit.io
• https://www.graphos.network/
• https://www.kumu.io/
• https://www.gliffy.com/examples/flowcharts
• https://sketchboard.io/
• https://www.academia.edu/18579547/A_Semantic_Wiki_Based_on_Spatial_Hypertext
• https://miro.com/
• http://www.liquid.info/dynamicview.html (dynamic view specifically)

Networked knowledge tools (closer to Roam)

• Roam Research
• Obsidian
• Athens Research
• Saga - capture memories (slightly different)
• Fibery
• Org Roam