What this tool does
JSON Validator
Your input is sent to the server for this request and is not saved as a tool content record. Infrastructure logs may still record request metadata, so do not submit secrets.
JSON Validator reports either Valid JSON or the line, column, and parser message for invalid syntax. Use it to find malformed quotes, commas, brackets, and braces.
A valid result confirms syntax only. It does not apply a JSON Schema, require fields, or verify application-specific values.
How to use this tool
How to validate JSON syntax
Paste JSON or upload a JSON or text file up to 1 MB.
Select Validate JSON.
For invalid input, inspect the reported line, column, and parser message.
Correct the source and validate again before using it in an API, import, or configuration file.
Before and after example
Valid JSON validation example
Input
{"company":"ScriptZip","tools":["json","api"],"active":true}Output
Valid JSONOptions, errors, and limitations
JSON syntax errors and validation limits
Parent category
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Validation-first tools for JSON and other structured developer content.
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FAQ
JSON Validator FAQ
What does a JSON validator actually check?
A syntax validator checks whether the input follows JSON grammar, including quotes, commas, brackets, braces, literals, and number formats. It does not automatically verify whether the data matches your application's required fields or business rules.
Does valid JSON mean it matches my API schema?
No. JSON can be syntactically valid while still missing required properties, using the wrong data types, or containing values the API rejects. Schema validation is a separate layer.
Why are JSON comments invalid?
Standard JSON does not define comment syntax. Configuration formats that look like JSON may allow comments, but strict JSON validators will reject them.
Why does a trailing comma make JSON invalid?
Standard JSON does not allow a comma after the last item in an array or the last member in an object. Remove the trailing comma before submitting the document.
Can a JSON validator detect duplicate object keys?
Some validators warn about duplicate keys, but behavior varies because parsers may keep the first value, the last value, or expose duplicates differently. Avoid duplicate property names because they create interoperability problems.
How do I find where a JSON syntax error occurs?
Good validators report a character position, line, column, or nearby token. Start at that location but also inspect the preceding line because a missing quote or comma earlier can cause the parser to fail later.
Can a browser JSON validator handle huge files?
Very large documents can exceed browser memory or take a long time to parse. For production scale logs or exports, use a streaming validator or command line parser.
Is formatting the same as validating JSON?
No, but a formatter usually needs to parse valid JSON first. A validator focuses on correctness, while a formatter focuses on readability after the syntax is accepted.
Are top level numbers, strings, booleans, and null valid JSON?
Yes under the current JSON specification. Although many APIs expect an object or array, JSON itself allows any JSON value at the top level.
Is JSON Lines the same as normal JSON?
No. JSON Lines or NDJSON stores separate JSON values on separate lines, which is not one single standard JSON document unless it is wrapped in an array or processed record by record. A normal JSON validator may reject a multi record JSON Lines file.