SEO Report Tools

Webmaster Utilities · Runs in your browser · Free

JSON Formatter & Validator

Validate JSON, locate syntax errors, and pretty-print or minify it.

What this tool does

Checks that JSON is valid, reports the line and column of the first problem and outputs a neatly formatted or minified version with optional key sorting.

Who should use it

Developers, and SEOs working with JSON-LD, APIs and exports.

How it works

The text is parsed with the browser's JSON parser, which follows the JSON specification strictly. Error positions are derived from the parser message.

How to use it

  1. Enter or paste json in the form.
  2. Adjust the options below the main box if you need to; the defaults suit most cases. Use "Load example" to see how input should look.
  3. Press the run button. Processing happens instantly in your browser.
  4. Review the result panel, then copy or download the output if the tool offers it. Use Reset to start over.

Practical example

{"a":1,} is reported invalid because of the trailing comma.

Understanding the results

The summary shows root type, depth and output size.

Limitations

Strict JSON only: comments, single quotes and trailing commas are errors. Very large inputs may slow the browser.

Accuracy and report transparency

Results are computed in your browser from exactly what you enter. Deterministic steps (counting, parsing, encoding, validation) are verified by an automated test-suite with known answers. Where a method is a heuristic, the result panel says "estimated". No external data is used and nothing is invented.

Privacy

Your input never leaves your device for this tool. We count anonymous events (tool opened, run, copied) without storing what you typed. See the Privacy Policy.

Try these next

JSON-LD ValidatorCheck JSON-LD syntax and verify basic required properties for common schema.org types.CSV to JSON ConverterConvert CSV with a header row into a JSON array of objects.JSON to CSV ConverterConvert a JSON array of objects to CSV with proper quoting.

Frequently asked questions

Is my JSON uploaded?

No, it is processed locally in your browser.

Is my data sent to your server?

No. This tool runs entirely in your browser, so the text or files you enter stay on your device. We do record anonymous counts of how often each tool is opened or run (no input data) to see which tools are useful.

How accurate are the results?

Counting, parsing, encoding and validation steps are deterministic and covered by automated tests with known answers. Anything based on a heuristic is labelled "estimated" in the result panel.

Is this tool really free?

Yes. There is no account, limit or paid plan. The site is supported by advertising, which is disclosed on our Advertising Disclosure page.

References