JSON formatter

Paste it, fix it, read it. Errors come with a line, a column and a fix. Your data never leaves this tab. Not even to us.

READY PASTE SOMETHING

Paste JSON on the left, or load the sample and break it on purpose.

INPUT
OUTPUT JSON 

            
            
            
          

        

      


      

        

          
          
          
        

        
      

    


    
EMPTY  PASTE OR DROP A FILE


    

      

        

          
Errors, located

          
A browser's own parser says "Unexpected token" and, if you are lucky, a character offset. This page has its own scanner that stops at the first thing it cannot accept, prints the line with a caret under the exact column, names the token, and says what to change. It knows the classics: a trailing comma, single quotes, an unquoted key, a missing comma or bracket, NaN, undefined, a comment, a leading zero, a stray =, a line break inside a string, and the invisible non-breaking space a chat window pasted in.

          
Jump to it puts the cursor on the spot in the input. Fix it, and the stamp turns as you type.

        

        

          
The query box

          
Paths are written the way you would in JavaScript: a.b[2].c, items[*].id, [-1] for the last item, ["key with spaces"] when a key needs it. A star fans out, so orders[*].lines[*].sku gives you every SKU in one flat list. Results update as you type and never touch the output pane.

        

        

          
Tree and CSV

          
The tree opens two levels and lets you unfold the rest; every node carries its type and its size. To CSV takes an array of objects, one row each, and flattens nested objects into dotted columns like address.city. An object with a single array inside it is unwrapped for you. Anything else becomes one row.

        

      


      

        

          

            Keyboard
            

              
Cmd or Ctrl + Enter
Format

              
Cmd or Ctrl + Shift + M
Minify

              
Esc in the query box
Clear the query

            

          

          

            This browser
            

              
            

            
Stored in this browser only, up to 256 KB, and cleared the moment you untick it.

          

          

            Big documents
            
Over a megabyte, the work moves to a background thread so the page stays responsive; the rule above the output shows progress. Tested with a generated 5 MB document.

          

        

      

    


    

      
What stays here

      
Everything on this page is plain JavaScript in your browser: JSON.parse and JSON.stringify for the fast path, a hand-written scanner for the error report, a Web Worker on the same origin for the big ones. There is no server doing the work, so there is nothing to send it to. Your document is not uploaded, not logged, and, unless you tick the box, gone when you close the tab. The only thing this page records is that a button was pressed, and which one.