fmtly
JSON Validator

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JSON Validator

Validates JSON syntax and reports errors with exact line and column numbers, plus a plain-language explanation. Includes a "Try Auto-Repair" option for common issues like trailing commas and single quotes.

Use Cases

  • Quickly check if a JSON string is syntactically valid
  • Find the exact location of a syntax error in a malformed API response
  • Validate JSON configuration files before deployment
  • Debug JSON parsing errors by getting human-readable explanations
  • Auto-repair common JSON issues from hand-edited files

Frequently Asked Questions

What JSON errors does this tool detect?

It detects all syntax errors including trailing commas, missing brackets, unquoted keys, single-quoted strings, duplicate keys, and unexpected tokens.

What does the auto-repair feature do?

Auto-repair attempts to fix common issues like trailing commas, single quotes around strings, unquoted property names, and missing closing brackets. It shows what was changed.

Can I validate JSON against a JSON Schema?

This tool validates syntax only. For validating JSON against a JSON Schema definition, use the JSON Schema Validator tool.