Json
- human readable/editable
- can be parsed without knowing schema in advance
- excellent browser support
- less verbose than XML
XML
- human readable/editable
- can be parsed without knowing schema in advance
- standard for SOAP etc
- good tooling support (xsd, xslt, sax, dom, etc)
- pretty verbose
Protobuf
- very dense data (small output)
- hard to robustly decode without knowing the schema (data format is internally ambiguous, and needs schema to clarify)
- very fast processing
- not intended for human eyes (dense binary)
All have good support on most platforms.
Personally, I rarely use XML these days. If the consumer is a browser or a public API I tend to use json. For internal APIs I tend to use protobuf for performance. Offering both on public API (either via headers, or separate endpoints) works well too.
