As simple as possible, JSON?

[dkotrada]

We try to keep Valder as simple and intuitive as possible mantaining it's elastic and quite powerful design.

Why don‘t you use for config files the Vala itself? Or .toml. https://en.m.wikipedia.org/wiki/TOML
They have much cleaner syntax than json files. I mean easier to read and write for people than json.

[activey]

Hmm, honestly, I was a little bit more familiar with JSON when I was developing Valder, maybe it would make more sense to use something different ...

[dkotrada]

Nice webpage for valder. But my first impression was: "he write it is simple but the wirst example seems to compicated for me". I think it is not attractive for first time visitors to your webpage. Take a look at this getting started page. It has some ideas to take for valder webpage. I mean step by step instead of complete config file.
There are more alternatives:
Human Json https://hjson.org or
YAML https://en.m.wikipedia.org/wiki/YAML

[activey]

Yeah, already got some suggestions about config file format, I agree it could be simpler ... Just had no time for changing that ...

[naaando]

I thought the same, what if it were done format agnostic?

[activey]

Sure, go ahead and try it :)