JSON Formatter & Validator

This tool takes JSON in any state — one long line from an API, a hand-edited config, a payload pasted out of a log — and returns it indented at the width you choose. Validation is not a separate button because it cannot be: the text is parsed with the browser's own JSON parser and re-serialised, so anything that formats successfully is valid by definition, and anything that fails reports the position where the parser stopped. Developers and support engineers use it to make a response readable before hunting through it, or to confirm a config file will actually load before shipping it. Key order is preserved and values are never rewritten or rounded. It accepts strict JSON only, so comments, trailing commas and single-quoted keys are errors here even though plenty of languages accept them. Document size is bounded by the memory available to the page rather than any fixed limit.