UE4/5 Dialogue Editor like Bioware's Dragon Age Origins.
Slate & C++. Open source.
Current license requires you to correctly answer: "Is it possible you are a human being?". Do not use this unless you provide the correct answer, to yourself.
Not production ready.
For new or existing complex multi-branching dialogues. But I guess it's better for new dialogues, the existing ones I used as a test are from Bioware. It also requires you to create your own plots data tables, some examples included, also from Bioware
Dump it in your Plugin dir of your project folder, can be a UE 4 or 5 project
e.g: China link https://www.bilibili.com/video/BV1R64y1W7Fn