What is the difference between formatting and validating?

Formatting adds indentation and whitespace to make JSON readable. Validating checks whether the structure is syntactically correct according to the JSON specification (RFC 8259).

Does it support JSONC (JSON with comments)?

No — comments are not part of the JSON standard. A file with comments is not valid JSON and will cause a parse error. Use a JSON5 or JSONC parser for those formats.

Can I minify JSON with this tool?

Yes — after formatting, use the Minify button to compact the JSON by removing all whitespace, producing the smallest possible valid JSON string.

JSON Formatter & Validator — How to Use

What is the JSON Formatter?

The Devbin JSON Formatter takes any JSON string and renders it with proper indentation, colour-coded types (keys in cyan, strings in green, numbers in orange, booleans in blue, null in red), and clear error messages when the JSON is invalid.

It also works as a validator — if the JSON contains syntax errors, it pinpoints the exact position and character that caused the problem.

How to Use It

Open the tool

Go to JSON & API and scroll to the JSON Formatter section.

Paste your JSON

Type or paste any JSON — a single object, an array, a minified API response, or a multi-level nested structure.

Read the output

Valid JSON is displayed formatted with syntax highlighting. Invalid JSON shows an error message with the position of the issue.

Copy or minify

Click Copy for formatted output, or Minify to get compact single-line JSON.

Common JSON Errors

⚠️Trailing comma — {"key": "value",} — JSON does not allow a comma after the last item. Remove the trailing comma.

⚠️Unquoted keys — {key: "value"} — JSON requires all keys to be in double quotes: {"key": "value"}.

⚠️Single quotes — {'key': 'value'} — JSON only allows double quotes, not single quotes.

⚠️Missing comma — {"a": 1 "b": 2} — Properties must be separated by commas.

Pro Tips

💡Use Minify to compact JSON before storing it in environment variables or passing it as a command-line argument.

💡The colour coding makes it immediately obvious if a value is the wrong type — e.g. a number stored as a string.

💡JSON keys must be unique within an object. Most tools accept duplicates, but the last value silently overwrites previous ones.

Frequently Asked Questions

What makes JSON invalid?

Common issues: trailing commas, unquoted keys, single quotes instead of double quotes, missing commas between properties, and unclosed brackets or braces.

Can I format nested JSON?

Yes — the formatter handles arbitrarily nested objects and arrays, indenting each level for readability.

Does it support JSONC (comments)?

No — JSON with comments is not standard JSON. Comments will cause a parse error. Use a dedicated JSONC parser or remove comments first.

Is my data sent to a server?

No — all formatting and validation happens in your browser using JavaScript. Your data never leaves your machine.

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