[gedrap]

But does it solve any actual problems other than 'XML is not cool', problems big enough to deserve a new format?

It's true that JSON is easier to deal with than XML. But that's relative, there are plenty of decent tools around RSS. From readers, to libraries in the most common programming languages, and extensions in the most common content management systems. JSON is slightly easier to read for human (although that's subjective), but then how often do you need to read the RSS feed manually, unless you are the one who is writing those libraries, etc. But that's a tiny share of all people using RSS.

>>> It reflects the lessons learned from our years of work reading and publishing feeds.

Sounds like the author(s) has extensive experience in this field and knows things better than some random person on the internet (me). But the homepage of the project doesn't convey those learned lessons.

[tannhaeuser]

Yes JSON is much easier to parse than XML, and is preferred when it fits such as for most Web API requests and responses.

However, SGML and XML were invented as structured markup languages for authoring of rich text documents by humans, for which JSON is unsuited and sucks just as much as XML sucks for APIs.

Edit: though XML has its place in many b2b and business-to-government data exchanges (financial and tax reporting, medical data exchange, and many others) where a robust and capable up-front data format specification for complex data is required