Fuzzing has been incredibly successful in uncovering bugs and vulnerabilities across diverse software systems. JSON parsers play a vital role in modern software development, and ensuring their reliability is of great importance. This research project focuses on leveraging Large Language Models (LLMs) to enhance JSON parser testing. The primary objectives are to generate test cases and mutants using LLMs for the discovery of potential bugs in open-source JSON parsers and the identification of behavioral diversities among them. We aim to uncover underlying bugs, plus discovering (and overcoming) behavioral diversities.