JSON Formatter & Validator

Paste JSON to format, validate or minify it — with instant error messages and syntax highlighting.


      

    


    

      
      Everything runs locally in your browser — your data is never sent anywhere.
    


    


    

      
About this tool

      
A one-line API response with twelve levels of nesting is technically valid JSON — and completely unreadable. This free tool formats, validates and minifies JSON with syntax highlighting, choosing between 2-space, 4-space or tab indentation. It's built for the everyday debugging loop: paste a payload, instantly see its structure, spot the field you're hunting for.

      
Crucially for developers, it runs 100% in your browser. API responses often contain tokens, emails or customer data — pasting them into a server-side formatter quietly ships that data to someone else. Here, nothing you paste ever leaves your machine.


      
How to format JSON

      
    
        
  1. Paste your JSON into the input panel.
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  2. Pick an indentation style, then hit Format — or Minify to strip whitespace.
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  3. Invalid input? The error message points at what's broken.
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  4. Copy the highlighted output or download it as a file.
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Frequently asked questions

      

        

          Is it safe to paste sensitive JSON here?
          
Yes — everything runs locally in your browser and nothing you paste is transmitted anywhere. That makes it safe for API responses, config files and payloads containing keys or personal data, unlike formatter sites that process input server-side.

        

        

          What does the validator tell me when my JSON is invalid?
          
The parser reports the error it hit, which usually pinpoints the problem: a trailing comma, a missing quote or bracket, or single quotes where JSON requires double quotes. Fix the reported spot and re-validate.

        

        

          What is the difference between formatting and minifying?
          
Formatting (pretty-printing) adds indentation and line breaks so humans can read the structure. Minifying strips all unnecessary whitespace into a single line for the smallest possible payload. Both produce exactly equivalent JSON.

        

        

          Which indentation should I use — 2 spaces, 4 spaces or tabs?
          
Pure preference; the data is identical. Two spaces is the most common convention in web development, four is easier to scan in deeply nested structures, and tabs let every reader choose their own display width.

        

        

          Can it handle large JSON files?
          
Yes — multi-megabyte payloads format fine; the practical ceiling is your browser's memory. For very large files, minified output will also render faster than pretty-printed output.