Online JSON Validator & Syntax Linter
Validate JSON syntax with precise line/column error markers, duplicate key detection, and instant safe-fix suggestions.
How It Works
Fast, secure, browser-native JSON processing in 3 simple steps
Paste or Upload JSON
Paste your raw data directly into the editor or upload any .json, .jsonc, or .json5 file.
Inspect & Validate
Instantly view syntax errors, health score, duplicate keys, and potential sensitive credentials.
Format, Diff or Export
One-click format, run structural comparisons, generate redacted copies, or download the clean output.
Actionable Error Diagnostics
Standard JSON parsers often return generic messages like "Unexpected token }". JSONForge analyzes the surrounding AST context to tell you precisely what went wrong — whether you forgot a comma between array elements, left a trailing comma before a closing bracket, or declared duplicate keys inside an object.
Frequently Asked Questions
Everything you need to know about JSON validation, formatting, and privacy
Related Developer Tools
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JSON Validator →
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Structural Diff Lab →
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