JSON Formatter & Validator

Paste messy JSON to see clean, indented output and quickly surface syntax errors. Everything runs locally in your browser.

Pretty Print Output
Error Highlighting
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Format JSON Learn Tips

JSON Formatter & Validator

Paste raw or minified JSON on the left, then format and validate it. If we find issues, we’ll highlight exactly where the parser stopped.

Your JSON Input

Accepts objects, arrays, and JSON5-style quotes.

Formatted JSON


                        
                        

                    

                

            

        

    


    

        

            

                
Tips for Working with JSON

                
Keep your JSON data clean and maintainable with these best practices.

            

            

                

                    
Common Formatting Mistakes

                    

                        
    
                            
  • Trailing commas cause parser errors in strict JSON. Remove them before submission.
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  • Wrap property names in double quotes unless you’re using JSON5-compatible tools.
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  • Validate that numbers are within expected ranges—JSON accepts large integers but your API might not.
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When to Minify

                    

                        
Minified JSON reduces payload size for APIs and configuration files. However, keep formatted copies in version control so diffs remain readable. Use environment-based builds to swap between minified and human-friendly outputs.

                    

                

            

        

    


    

        

            

                
Frequently Asked Questions

                
Learn more about formatting and validating JSON safely.

            

            

                

                    

                        Will my JSON data leave the browser?
                        
                    

                    

                        
No. All parsing happens locally with built-in browser APIs so your data stays on your device.

                    

                


                

                    

                        Does this support comments or trailing commas?
                        
                    

                    

                        
The formatter accepts JSON5-style input (single quotes, comments, trailing commas) but outputs strict JSON to maintain compatibility with APIs.

                    

                


                

                    

                        Can I pretty-print large JSON files?
                        
                    

                    

                        
Yes, but extremely large files might slow down your browser. For multi-megabyte payloads, consider command-line tools or streaming parsers.