01
Valid flat object
Validate {"name":"Ada","age":30} to see it marked Valid JSON, reported as an Object with 2 keys at depth 1.
JSON Validator
Data ToolsValidate JSON online and find the exact line of any syntax error — free JSON checker.
About
About the JSON Validator
Checks whether a block of JSON parses correctly, and shows structure details or the exact error position if it doesn't.
API developers use it to sanity-check a response body before writing code against it, while support and QA teams use it to quickly confirm whether a customer-submitted JSON payload is even valid before digging further. It's one of many free data tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.
Examples
JSON Validator examples
4 worked examples
02
Valid nested array
Validate {"users":[{"id":1},{"id":2}]} to see it marked Valid JSON, reported as an Object with 1 key at depth 3.
03
Trailing comma caught
Validate {"a":1,} and it's marked Invalid JSON, since trailing commas aren't allowed in strict JSON.
04
Syntax error location
Validate {"a": 1 "b": 2} (missing comma) and it's marked Invalid JSON, with the message pointing to the exact line and column where parsing broke.
Related tools
FAQ
Frequently asked questions
Quick answers to common questions about the JSON Validator.
What does the JSON Validator do?
It checks whether JSON parses correctly, and shows either structure details (for valid JSON) or the exact error position (for invalid JSON).
Is the JSON Validator free to use?
Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.
Is my JSON safe when I use this tool?
Yes. Validation runs entirely in your own browser using JavaScript's built-in JSON parser — nothing you paste is sent to a server.
How does it find the error position?
It reads the position the browser's JSON parser reports for the failure and converts it into a line and column number, along with the surrounding text, so you can find the exact spot faster.
What does "nesting depth" mean?
It's how many levels of objects and arrays are nested inside each other, counted from the outermost value. A flat object with no nested objects or arrays has a depth of 1.
Does this tool fix invalid JSON for me?
No. It only tells you that the JSON is invalid and where the problem is — you make the fix and validate again.
Can I use the JSON Validator on my phone?
Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.
Does the JSON Validator have any limitations?
It follows the strict JSON spec, so JavaScript-only syntax like trailing commas, comments or unquoted keys will be reported as invalid, even though some JavaScript engines tolerate them.