Comments in JSON

JSON does not have comments. A JSON encoder MUST NOT output comments. Douglas Crockford - creator of json

Want to use comments in JSON even though Douglas doesn’t want you to :)

Using ini, apache, xml, html or // comment formats invalidate your JSON files


    "name": "Jack (\"Bee\") Nimble", //varchar
        "format": {
            "type":       "rect", //varchar - max 4 characters
            "width":      1920, //int
            "height":     1080, //int
            "interlace":  false, //boolean
            "frame rate": 24 //int

As Douglas stated, JSON has no offical support for comments, but it doesn’t mean you can’t add them in other ways

The best way I’ve found to add comments into JSON is to add _comment style elements - after the element your commenting on - into the JSON. Refer below for a valid JSON file with comments.


    "name": "Jack (\"Bee\") Nimble", 
        "format": {
            "type":       "rect", 
            "_type_comment": "varchar - max 4 characters",
            "width":      1920, 
            "_width_comment": "int",
            "height":     1080, 
            "_height_comment": "int",
            "interlace":  false, 
            "_interlace_comment": "boolean",
            "frame rate": 24,
            "_frame_rate_comment": "int"


  • Make sure your app ignores the _comment elements
  • Use to validate your JSON

Let me know if you have a better way to do valid comments in JSON

Justin Kelly

Justin Kelly

Data Engineeer, Business Analytics, Web Developer, Library Technology specialising in PHP and Tableau

Based in Melbourne, Australia

Feel free to contact me or _justin_kelly