JSON Validator
Check JSON syntax locally and flag repeated object property names.
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Load the fictional example in a cleared form. Check the options, run the tool if needed, and compare the result below.
Check whether pasted text can be parsed as JSON in the browser. A valid result confirms syntax only, not the application’s schema or business rules. Paste JSON to check syntax. If object property names repeat, the result warns that parsers may retain different values. A clean result confirms syntax and unique names only; it does not check your application schema or business rules. A successful check covers JSON syntax and repeated property names only; it does not validate required fields, types, permissions, or application rules.
JSON input
{"name":"Ada","count":2,"active":true}Expected output
Valid JSON syntax. No duplicate property names detected.
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Text is processed in your browser.
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Quick answer
Check whether pasted text can be parsed as JSON in the browser. A valid result confirms syntax only, not the application’s schema or business rules.
The page and its assets load from the site; this operation uses your entered values only in this browser and does not send them to a calculation endpoint.
How to use it
Paste JSON to check syntax. If object property names repeat, the result warns that parsers may retain different values. A clean result confirms syntax and unique names only; it does not check your application schema or business rules.
Limits
A successful check covers JSON syntax and repeated property names only; it does not validate required fields, types, permissions, or application rules.
Frequently asked questions
What does a valid result tell me?
It tells you the text parses as JSON and has no repeated object property names. It does not confirm required fields, data types, permissions, or business rules.
Why does the validator warn about repeated property names?
JSON recommends unique object names, but parsers may handle duplicates differently. Remove the duplicate or check the data with the same parser that will consume it.
Why is a trailing comma an error?
JSON syntax does not allow a trailing comma after the last item in an object or array.
Does validation upload the JSON?
The syntax check runs in the browser; loading the page still requests its code and assets from the site.
Sources and references
These references document the cited standard or browser API; they do not validate the tool’s output.