Validate JSON
Paste JSON to check its syntax, see where an error occurs, inspect the root type and size, then copy or download formatted output.
A QUICK WALKTHROUGH
How to use this tool
- Paste one JSON value up to 100,000 characters.
- Select Validate JSON to inspect syntax, parser position, and a type summary.
- Copy or download the formatted JSON when the value is valid.
Useful parser diagnostics
Invalid JSON stays in the page and reports the browser parser message plus the nearest line, column, and character position when available. Trailing content, malformed strings, and unsupported syntax are rejected.
Bounded and local
Inputs are limited to 100,000 UTF-16 characters and are processed entirely in your browser. This page never evaluates pasted text as JavaScript or uploads it to a server.
GOOD TO KNOW
Common questions
Which JSON values are accepted?
Objects, arrays, strings, numbers, booleans, and null are all valid JSON roots.
Does validation execute code?
No. It uses JSON.parse only; JSON cannot call functions or run scripts.
Can I save the formatted result?
Yes. After a successful validation, copy the formatted value or download it as a .json file.