Subject to changeVersion 6 is currently in beta, so the API
Unless you need the new features of version 6 (e.g. MessagePack), please use version 5.
Version 6 should stay in beta stage until 2019.
JsonDocument is the entry point for using the library: it handles the memory management and calls the parser.
It implements a speed efficient memory pool and comes in two flavors:
DynamicJsonDocumentwhich is allocated on the heap and grows automatically
StaticJsonDocumentwhich is (most likely) allocated on the stack and has a fixed size.