Pinpoint JSON errors fast
Paste JSON and the validator checks it against the JSON standard (RFC 8259) as you type. Valid input shows a green confirmation along with useful stats: the number of keys, arrays and values, how deeply it's nested and its size in bytes. Invalid input shows the line and column of the first error with the surrounding text, so you don't have to count characters in a 5,000-line file.
The most common problems — trailing commas, single quotes, comments, unquoted keys and values like undefined or NaN — come from writing JSON the way you'd write JavaScript. The auto-fix button rewrites them into valid JSON while leaving the contents of your strings untouched.
How to validate JSON
- 1
Paste the JSON
Or open a .json file from your computer.
- 2
Read the result
A success message with stats, or the error location.
- 3
Repair if needed
Use the auto-fix, or edit the reported line.
Key features
Standards-based checking
Uses the browser's own strict JSON parser.
Error location
Line, column and a pointer to the character.
Structure stats
Key count, nesting depth, arrays and total size.
Safe auto-fix
Repairs JavaScript-style syntax without touching string values.
Common uses
- Before deploying config: Catch a broken settings file before it takes your app down.
- Checking webhook payloads: Confirm a third party is sending well-formed JSON.
- Learning JSON: See precisely which rule a mistake breaks.
Tips and good to know
- JSON keys must use double quotes.
{name: "Ana"}is valid JavaScript but invalid JSON. - To make valid JSON readable, switch to the JSON Formatter.