Free JSON Formatter & Validator
Paste JSON and format it instantly. Validates syntax, highlights errors. Runs in your browser. Your data never leaves your device.
What it does
JSON formatting takes compressed or single-line JSON and adds indentation and line breaks. API responses, configuration files, and log output become readable documents you can scan and understand.
The validator checks for syntax errors as you type: missing commas, unquoted keys, trailing commas, mismatched brackets. A green or red indicator below the editor shows whether the current content is valid JSON.
All processing uses the browser's built-in JSON.parse and JSON.stringify. Nothing is uploaded, and no external libraries are needed.
JSON Formatter FAQ
What does a JSON formatter do?
It adds indentation and line breaks to make JSON readable. Compressed or single-line JSON becomes a structured document you can scan and edit. Also called a JSON beautifier or JSON prettifier.
Does it validate my JSON?
Yes. If the JSON has syntax errors (missing commas, mismatched brackets, unquoted keys, trailing commas), the validator shows the error and its location. Valid JSON shows a green indicator below the editor.
Can I minify JSON too?
Yes. The Minify button removes all whitespace, producing the smallest possible valid JSON. Useful for reducing payload size in API responses or configuration files.
Is my data safe?
Yes. Everything runs in your browser using built-in JSON.parse and JSON.stringify. No data is uploaded, stored, or sent anywhere. You can verify this in your browser's network tab.
What's the maximum file size?
Up to 1 MB, same as other MinifyTools. For larger files, use a command-line tool like jq.