JSON (JavaScript Object Notation) is the lingua franca of the modern web — APIs, config files, and databases all speak it. But real-world JSON arrives minified into an unreadable single line, or broken by a single misplaced comma. This free JSON formatter and validator beautifies, minifies, and diagnoses JSON with exact error messages.
Beautifying (pretty-printing) expands JSON into indented, human-readable structure — essential for debugging API responses. Minifying does the reverse, stripping whitespace for production payloads. Validation tells you precisely what is wrong (“unexpected token at position 42”) instead of a silent failure.
All parsing happens locally in your browser — sensitive API keys and payloads are never uploaded anywhere, making this safe for production data.
How to use the JSON Formatter & Validator
- Paste your JSON into the input box.
- Click Beautify for readable indented output, Minify for compact output, or Validate for a pass/fail check.
- Read any error message — it names the exact problem and position.
- Copy the output back into your code or API client.
Tips for accurate results
- Trailing commas are the #1 JSON error — JSON forbids them, unlike JavaScript.
- Keys must be double-quoted: {name:...} is invalid, {"name":...} is valid.
- Use single quotes? JSON requires double quotes for all strings.
- Validate API responses before blaming your code — malformed JSON is common.
Common JSON errors and fixes
Trailing commas after the last item, single-quoted strings, unquoted keys, and comments (JSON has none) account for nearly all failures. The validator flags each with its position so you can fix it in seconds.
Frequently asked questions
What is JSON?
JavaScript Object Notation — a lightweight, text-based data format using key-value pairs and arrays. It is the standard for web APIs and configuration.
What does ‘beautify’ mean?
Pretty-printing: expanding compact JSON into indented, multi-line form that humans can read and debug.
Why is my JSON invalid?
Most often: trailing commas, single quotes instead of double quotes, unquoted keys, or comments. The validator reports the exact issue.
Is my JSON data uploaded anywhere?
No. Parsing and formatting run entirely in your browser via JavaScript — nothing is sent to any server.