JSON Formatter

Paste minified or messy JSON and instantly get clean, indented, readable output. Validates syntax and pinpoints errors to the exact line.

Input JSON
Waiting for input…
Indent:
Formatted Output Valid JSON 

        

    


    
    

        
What is a JSON Formatter?

        
A JSON formatter (also called a JSON pretty printer or JSON beautifier) takes compact or minified JSON and adds whitespace — line breaks and indentation — to make it human-readable. Minified JSON packs everything onto a single line to reduce file size, which is efficient for transmission but impossible to read by eye. Formatting reverses that process so you can inspect the structure, spot incorrect values, and edit it confidently.

        
This tool runs entirely in your browser using JavaScript. Your data is never sent to any server, which makes it safe to use with API keys, internal payloads, or any sensitive JSON.


        
When should you format JSON?

        
    
            
  • Debugging API responses — when your app receives a minified JSON response, formatting it instantly reveals the full structure so you can identify wrong or missing fields.
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  • Code review — formatted JSON diffs are far easier to read than a single-line diff. Reviewers can see exactly what changed at a glance.
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  • Writing documentation — paste clean, indented JSON examples into API docs, Postman collections, or README files so readers understand the shape of the data.
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  • Config file maintenance — always keep JSON config files formatted so teammates can edit them without parsing a wall of text.
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  • Validating structure — formatting also validates syntax. If your JSON has a trailing comma or mismatched bracket, the error is shown immediately with a line number.
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Indentation styles: 2 spaces, 4 spaces, or tabs?

        
The three options produce identical JSON — only the whitespace differs. 2 spaces is the most common default in JavaScript tooling (Prettier, ESLint) and keeps files compact while still readable. 4 spaces is preferred in Python and some Java style guides. Tabs are preferred by developers who use accessibility tools or rely on configurable tab-width settings in their editor. Choose whichever matches the style guide of the project you are working on.


        
JSON formatting vs JSON validation

        
Formatting and validation are related but different. This tool validates your JSON first — if the syntax is invalid, formatting is disabled and the error is shown with the exact line number. Once the JSON is valid, formatting reformats it with the indentation style you choose. If you want a detailed structural report (key count, depth, array counts), use the dedicated JSON Validator.


        
Keyboard shortcuts

        

            Ctrl + Enter — Format JSON   
            Ctrl + M — Minify
        


        
Frequently asked questions

        

                        

                

                    
                

                

                    
No. Formatting only adds or removes whitespace. The keys, values, arrays, and objects remain identical. A JSON parser treats {"a":1} and { "a": 1 } identically — the whitespace has no semantic meaning in JSON.

                

            

                        

                

                    
                

                

                    
The Format button is disabled when the JSON input contains a syntax error. The error message shown below the input box (in red) explains what is wrong and which line it is on. Fix the error first, then format.

                

            

                        

                

                    
                

                

                    
Yes, but browser-based tools have practical limits. Files under 1 MB format instantly. Files between 1 MB and 5 MB may take a second. Files larger than 10 MB may slow down the browser tab. For very large files, consider using a command-line tool like jq (jq . file.json) which has no size limit.

                

            

                        

                

                    
                

                

                    
The terms are used interchangeably and describe the same operation. Some tools use "formatter" to emphasise standards compliance (indentation, key ordering), while "beautifier" emphasises the visual transformation from compact to readable. This tool does both.

                

            

                        

                

                    
                

                

                    
No. All formatting happens in your browser using the built-in JSON.parse() and JSON.stringify() functions. Nothing is transmitted to MockServer or any other server.

                

            

                    


        

            Related tools:
            JSON Beautifier
            JSON Validator
            JSON Diff
            JSON Repair
            JSON Minify
            All Tools