How to format JSON and find the error

What is JSON?

A text format for exchanging data between systems, used by most APIs and store platforms. Its rules are strict: keys in double quotes, no comma after the last item, no comments. One small mistake makes the whole file invalid.

{"b":[1,2],"a":{"c":null}}

Where is the error?

A 3-line text made of an opening brace, then "a": 1 with a comma, then a closing brace, is invalid because of the trailing comma. The tool places the error at line 3, column 1: the closing brace where a key name was expected. The tool never fixes errors on its own; it shows you where they are so you decide.

How to do it

1. Open the JSON formatter and validator and paste your JSON, or open a file.
2. Choose formatting with 2 or 4 spaces or a tab, or minify it onto one line.
3. If there is an error, read the message, line and column, and correct the text.
4. Copy or download the result.

What to know

• The limit is 5 MB. A file of that size was formatted and displayed in about 3 seconds.
• Integers above 9007199254740991 lose precision in JavaScript, and the tool warns you. Store them as strings if they are IDs.
• If a key repeats in the same object, only the last value survives, and the tool lists the repeated keys.
• The error message comes from your browser in English, and differs slightly between browsers.

If your data is a table you want to open in Excel, convert it with the CSV and JSON converter. If you find a Base64-encoded value inside the JSON, decode it with the Base64 encoder/decoder tool.