TiddlyRoam is described as 'is your open source external brain. TiddlyRoam allows you to quickly create your own wiki. You can add fragments of thoughts and findings whenever they come to you. TiddlyRoam will link them and help you spot the patterns' and is a Note-taking tool in the office & productivity category. There are more than 25 alternatives to TiddlyRoam for a variety of platforms, including Windows, Online / Web-based, Mac, Linux and Android. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Evernote or TiddlyWiki. Other great apps like TiddlyRoam are Obsidian, Org mode, Roam Research and SiYuan.
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.
As easy to use as a word document or bulleted list, and as powerful for finding, collecting, and connecting related ideas as a graph database. Collaborate with others in real time, or store all your data locally.