JSON Validator and Formatter

Validate JSON, format it for reading, or minify it for compact API payloads without sending data to an external API.

JSON output 

        

    

                

            
                    

                        
How to use this tool

                        
    
                                                            
  1. Paste JSON into the input area.
    2. 
                                                            
  2. Use Validate to check syntax, Format to pretty print, or Minify to compact it.
    3. 
                                                            
  3. Copy the output after validation succeeds.
    4. 
                                                    

                    


                    

                        
Common mistakes

                        
    
                                                            
  • Trailing commas after the last object or array item.
    • 
                                                            
  • Single quotes instead of double quotes for JSON strings.
    • 
                                                            
  • Comments inside JSON payloads.
    • 
                                                    

                    


                    

                        
FAQ

                        

                                                            

                                    Is the JSON sent to a server?
                                    
No. The validation runs locally in your browser.

                                

                                                            

                                    Can it fix invalid JSON automatically?
                                    
No. It reports parse errors and formats valid JSON.

                                

                                                            

                                    Can I validate OpenAI API JSON here?
                                    
Yes for generic JSON syntax. Use the OpenAI API Request Checker for API-specific warnings.

                                

                                                    

                    


                        

        
Related tools

        

                                                
                        OpenAI
                        OpenAI API Request Checker
                        
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Related guides and fixes

        

                                                
                        OpenAI
                        Debug OpenAI API Request JSON Before Sending
                        
Most API request bugs are easier to fix before the request is sent. Start with valid JSON, then check model-family parameters and only then debug application code.

                    
                                                                
                        cURL
                        cURL API Debugging Workflow for Developers
                        
cURL is the simplest way to separate API behavior from SDK, framework or frontend code. Build a minimal request first, then compare it with the failing implementation.

                    
                                                                            
                        JSON
                        JSON Trailing Comma Error Fix
                        
JSON is stricter than JavaScript object literals. Trailing commas, comments and single-quoted strings can break API requests and config files.

                    
                                                                
                        OpenAI
                        OpenAI max_tokens vs max_completion_tokens Error
                        
This error usually appears when a request body mixes parameters from different OpenAI model families. Validate JSON first, then align token fields with the target model.

                    
                                    

    

                        
Last updated: May 17, 2026