Format JSON

JSON is a text format for structured data. It replaced XML for most APIs by being smaller and quicker to read, without giving up the ability to describe nested structures. A JSON document is just a string, with a handful of characters carrying all the meaning:

• {}Braces hold an object — an unordered set of key/value pairs.
• []Brackets hold an array — an ordered list of values.
• ""Double quotes wrap every string, and every key.
• :A colon separates a key from its value, which may itself be an object or an array.

Why does {name:'json'} fail validation?

JSON requires double quotes on both keys and string values, so that has to be {"name": "json"}. Single quotes and bare keys are valid JavaScript object literals, not valid JSON — which is the single most common reason a payload that looks fine gets rejected.

Why is my trailing comma an error?

JSON does not allow a comma after the last element of an object or array. {"a": 1,} is invalid. JavaScript, Python, and most linters tolerate it, so it survives right up to the point something strict parses it.

Can I include a comment?

No. JSON has no comment syntax, which is why formats like YAML and TOML exist for configuration files that humans maintain. If you need comments in a config, convert to one of those.

Is my data uploaded anywhere?

No. Every tool on this site runs in your browser. Nothing is sent to a server, so you can paste a production payload without it leaving your machine.