What is JSON and how to format it correctly

JSON (JavaScript Object Notation) is the most common data interchange format on the web. It is lightweight, human-readable, and supported in virtually every programming language.

JSON is built on two structures: key/value pairs (objects) and ordered lists (arrays). Strings must be in double quotes, keys must always be strings, and trailing commas are not allowed.

A JSON formatter pretty-prints messy JSON to make it readable, validates its structure, and tells you exactly where the syntax breaks. Use ours at /tools/json-formatter — it works entirely in your browser, so nothing leaves your machine.

Common mistakes: • Using single quotes — JSON requires double quotes. • Trailing commas after the last item. • Unquoted keys — every key must be a string. • Comments — the JSON spec does not allow them. For configs that need comments, use JSON5 or YAML.

A quick tip: when working with APIs, always run the response through a formatter before reading it. You will spot errors much faster.