Question 1

How do I format JSON online?

Accepted Answer

Paste your JSON into the input panel above. The formatter instantly validates and pretty-prints it with 2-space indentation and syntax highlighting. If there's a syntax error, you'll see the exact line and character position of the problem. No button needed — formatting happens in real time.

Question 2

What does a JSON formatter do?

Accepted Answer

A JSON formatter (also called a JSON beautifier or pretty-printer) takes minified or compressed JSON and outputs it with proper indentation, line breaks, and syntax highlighting to make it human-readable. It also validates that the JSON is syntactically correct and highlights any errors.

Question 3

Why is my JSON invalid?

Accepted Answer

Common JSON errors include: trailing commas after the last item in an array or object, single-quoted strings (JSON requires double quotes), unquoted keys, comments (JSON has no comment syntax), undefined values, and NaN or Infinity (not valid JSON numbers). The formatter shows the exact error location.

Question 4

What is valid JSON syntax?

Accepted Answer

Valid JSON requires double-quoted string keys and values, no trailing commas, no comments, and values must be strings, numbers, booleans (true/false), null, arrays, or objects. Single quotes, JavaScript-style comments (//, /* */), and undefined are all invalid in JSON.

Question 5

How do I minify JSON?

Accepted Answer

Minified JSON removes all whitespace — spaces, newlines, and indentation — to reduce file size. A 100KB formatted JSON file might shrink to 30–50KB minified. Toggle to Minify mode in this tool, or use the dedicated JSON Minifier tool.

Question 6

What is the difference between JSON and a JavaScript object?

Accepted Answer

JSON is a data interchange format with stricter rules than JavaScript object literals. JSON requires double-quoted keys, forbids trailing commas, comments, functions, undefined, and Date objects. Use JSON.parse() to convert a JSON string to a JS object and JSON.stringify() to go the other way.

Question 7

What is the difference between JSON and JSONC?

Accepted Answer

JSONC (JSON with Comments) allows // and /* */ comments, used in VS Code settings files and tsconfig.json. Standard JSON (RFC 8259) forbids all comments — any parser will reject them. This formatter validates strict JSON. For JSONC, strip comments first. JSON5 is another superset allowing comments, trailing commas, and unquoted keys — useful for config files but not API payloads.

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