Every AI agent and developer runs into broken or confusing JSON constantly. This tool handles all the most common JSON headaches in one place: check if JSON is valid (with exact error location), fix near-JSON that has typos or formatting mistakes, pretty-print or minify, pull out specific values using a path expression, compare two JSON documents and see exactly what changed, convert to and from YAML or CSV, produce a byte-stable canonical form for hashing or signing, validate against a schema, and get size and structure statistics. Same input always gives the same output — fully predictable, no side effects.