Hi folks!
I ported FlexBuffers, a schema less, JSON comparable, binary serialisation format, used at Google to C# and implemented some useful Unity Editor tools.
You can check it by adding
"com.mzaks.flexbuffers": "https://github.com/mzaks/FlexBuffersUnity.git",
to your manifest.json file.
If you need more convincing, please have a look at this article:
Let me know what you think and if it might be useful for your game.