[Ultramanoid]

Check https://tiddlywiki.com

It can be as complicated or as simple as you want to make it. Can be used locally only or deployed on a server. Single self-contained html file, can be encrypted too.

[bythckr]

Managing tag is quite difficult. The TagCloud plugin is also not working well.

[h0p3]

I use two tools inside TW for tag management:

https://philosopher.life/#%24%3A%2FCommander:%24%3A%2FComman...

Bimlas' Locator blew my mind. I've never used anything like it before. That is worth checking out.

If you go the TW5-Bob route, building commandline tools for tags is also a great option.