Not your parent, but I've recently toyed with TiddlyWiki, which shows promise, but requires heavy configuration.

There is also an extension to it called TiddlyMap which displays several of the properties mentioned in this article (edges with properties, etc), but again, requires configuration to get just so.

If you're game to do some tinkering, I've found it to be hackable to some very deep levels. Another nicety is that it's all just a single HTML file, so it's madly portable (I can use the same site on my phone and laptop).

All this being said, there is a growing list of features that I would like to see in Tiddlywiki that I'm not sure I can hack in myself, so I suppose I, too, am looking for the "one true knowledge management" solution

Just start with Apache Jena, standards based with RDF as the exchange format and SPARQL for the query language. Others solutions may use proprietary stuff for better vendor lock-in: This is completely up to you if you want that. But with Apache Jena you can change later to other KG databases. Also: Apache Jena is easy to work with, since it includes Fuseki to start directly using it as a web API.

https://jena.apache.org/ https://jena.apache.org/documentation/fuseki2/

Once you need "big data" for your personal Knowledge Graph, you can use other RDF stores, without vendor lock-in.

There is TheBrain, which has a free-of-charge personal offerring, as well as aid service tiers.

Jerry Michalsky is among the more notable users.

https://www.jerrysbrain.com

http://old.thebrain.com/store/faq/#Section1.1

I've been working on building a personal knowledge database tool recently, feel free to shoot me an email at antimatter15@gmail.com if you'd like to be one of the first to try it out.

if you are after a graph database for personal use - Segrada (Segrada.org) is a nice open source UI on top of OrientDB.

Otherwise see Marviel and DredMorbius's suggestions both are worth checking out.

It depends on your needs, maybe try the SaaS app https://kumu.io/ or https://graphcommons.com/