JSON Formatter & Validator
How to use the JSON Formatter & Validator
Paste JSON into the box and click Format to add readable indentation, Minify to remove all unnecessary whitespace, or Validate only to check it without changing it. If the JSON is invalid, the tool shows the parser’s error message and, where the browser provides it, the line and column to look at. Your data is parsed locally and never sent to a server.
Example
Input: {"name":"Freetoolza","tools":[1,2,3]}. After formatting with two spaces, each key and array item appears on its own indented line, which makes nested data easy to scan. Minifying reverses this to a single compact line, useful for smaller payloads.
Common JSON mistakes
- Trailing commas after the last item in an object or array
- Single quotes instead of double quotes around keys and strings
- Unquoted keys such as
{name: "x"} - Comments, which standard JSON does not allow
- Missing commas between items or unclosed brackets
Common uses
- Reading API responses and log output
- Debugging configuration files
- Checking JSON before sending it to an API
- Reducing the size of JSON by minifying
Frequently asked questions
Is my JSON uploaded?
No. Parsing and formatting use your browser’s built-in JSON support.
Does formatting change my data?
Only whitespace changes. One exception: very large numbers can lose precision because JavaScript stores numbers as 64-bit floats, and duplicate keys keep only the last value.
Can it fix invalid JSON automatically?
No. It reports the problem so you can fix it yourself.
Limitations
Very large inputs may slow down your browser. Error positions depend on your browser and may be approximate. Avoid pasting secrets such as API keys into any website. See our Disclaimer and Privacy Policy. Browse the full tools directory. Related tools: JSON Template Creator, URL Encoder & Decoder.