JSONKit

JSONKit is a high-performance Objective-C library for parsing and generating JSON on iOS and macOS, created before Apple’s built-in JSON APIs were widely available. It focuses on speed and low memory overhead, using tight C/Objective-C code paths to turn NSData into Foundation containers (arrays, dictionaries) and back again. The API provides flexible options such as mutable or immutable containers, pretty printing, and tolerances for common JSON formatting quirks. Developers can stream or parse in one shot, and they get predictable error reporting when malformed input is encountered. Because the output is standard Foundation objects, it drops into existing code with minimal adaptation. Even as the platform matured, JSONKit remained a reference point for how to write fast, reliable serialization code on Apple platforms.