Feign makes writing java http clients easier
A fast JSON parser/generator for Java.
Generate Java types from JSON or JSON Schema and annotates those types for data-binding with Jackson, Gson, etc
A reference implementation of a JSON package in Java.
JSON to JSON transformation library written in Java.
A JSON Schema validation implementation in pure Java, which aims for correctness and performance, in that order
Logback JSON encoder and appenders
jsoniter (json-iterator) is fast and flexible JSON parser available in Java and Go