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Check your JSON syntax instantly. Get clear, human-readable error messages showing the exact line and column of every JSON syntax error. Works entirely in your browser.
A JSON validator checks whether a string of text is valid JSON according to the RFC 8259 specification. Valid JSON has strict syntax rules: object keys must be double-quoted strings, values must be one of string, number, boolean, null, object, or array, and trailing commas are not permitted. A single misplaced comma or unquoted key will cause any JSON parser to throw an error.
JSON Viewer Pro's online JSON validator runs in real time as you type. It checks your JSON syntax with a short debounce so large files don't slow down the editor. When an error is found, you see the exact line and column number alongside a plain-English explanation — not just "SyntaxError: Unexpected token". The Monaco editor also places a red error marker directly on the offending line, so you can jump straight to the problem.
Common JSON validation errors include trailing commas after the last property in an object or array (valid in JavaScript but not in JSON), single-quoted strings instead of double-quoted strings, unquoted property keys, and missing colons or commas between values. The validator detects all of these and explains each one clearly, making it easy to fix JSON errors even if you're not deeply familiar with the JSON specification.
It checks your JSON for syntax errors, such as missing commas, unquoted keys, or incorrect brackets, and tells you exactly where the problem is.
Trailing commas, missing quotes around keys, single-quoted strings, and mismatched brackets are the most common JSON syntax errors.
Yes. Validation runs as you type, with a short debounce to avoid slowing down large files.
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