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JSON validator — validate and lint JSON online

Paste JSON data and instantly detect syntax errors with line numbers and descriptive error messages

JSONJavaScriptTypeScriptCSSHTMLYAML
JSON validator
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JSON-specific

Why validate your JSON?

Invalid JSON is one of the most common causes of API failures, configuration errors, and data pipeline breakages. A missing comma, an extra trailing comma, an unescaped quote inside a string value — any of these makes the entire document unparseable. QuickKit's JSON validator parses your input using the same native JSON.parse used in every JavaScript runtime, providing the exact error message and line number so you can fix the problem immediately. Unlike browser DevTools which show cryptic parse errors, QuickKit formats the error clearly with position information and a description. Validate webhook payloads, API responses, configuration files, and data exports before using them in your application.

Questions

Frequently asked questions

This validator checks JSON syntax (well-formedness). JSON Schema validation — checking that values match a schema definition — is a separate feature on the roadmap.
No — trailing commas are not valid JSON even though they're allowed in JavaScript objects. The validator flags them as syntax errors.
The native parser allows duplicate keys (last value wins). QuickKit warns when duplicate keys are detected since they often indicate a data bug.
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