Invalid JSON? How to Find and Fix the Error

1. 1

   Paste the JSON

   Paste it into JSON Formatter. It checks the text as you type or paste, in your browser.

2. 2

   Read the line and column

   If the JSON is invalid, the formatter shows the error message with the line and column where parsing failed. The real mistake is usually at that spot or just before it.

3. 3

   Fix and format

   Correct the mistake, then format the result with 2 spaces, 4 spaces or tabs. Proper indentation makes the next problem, if there is one, easy to see.

These cause the vast majority of invalid JSON:

• A trailing comma after the last item in an object or array, such as [1, 2, 3,]. JavaScript allows it; JSON does not.
• Single quotes. JSON strings and keys must use double quotes, so {'name': 'Ana'} is invalid and {"name": "Ana"} is valid.
• Keys without quotes, such as {name: "Ana"}. Every key must be a quoted string.
• Comments. JSON has no // or /* */ comments, so remove them or move them into a separate field.
• Curly quotes pasted from a word processor or chat app instead of straight double quotes.
• Values JSON does not know: undefined, NaN, Infinity, or dates written without quotes. Use null, a number, or a quoted string instead.
• A missing comma between two items, which usually shows up as an error at the start of the second item.
• Two separate JSON objects one after the other without being wrapped in an array.

Browsers phrase errors differently, but they point at the same thing. "Unexpected token" means the parser met a character it did not expect at that position, such as a quote of the wrong kind or a stray comma. "Unexpected end of JSON input" means something was opened and never closed: a missing closing brace, bracket or quote, often caused by a file that was cut off while copying or downloading. "Expected property name" usually means a trailing comma or an unquoted key inside an object.

Once the JSON parses, format it consistently and, if the order of keys does not matter, use Sort Keys so that two versions can be compared line by line. The tree view is handy for checking the structure of a large response without scrolling through it. When you need the data in a spreadsheet rather than in code, convert it to CSV; the JSON to Excel guide shows how to open the result cleanly.