THE JSON KIT

JSON Validator & Auto-Fixer

The definitive tool to validate JSON against RFC 8259 standards. Detect syntax errors, auto-fix missing quotes, and repair broken JSON instantly.

Ready to Validate

Paste code or upload file.

Editor

Quick Tips

  • Keys must be in double quotes "key".
  • No trailing commas after the last item.
  • Use null for empty values.
  • Click Auto Fix to repair standard JS objects.

How to Validate & Fix JSON

  1. Input Data: Paste your JSON code directly into the editor. Validation runs instantly.
  2. Identify Errors: If the status bar turns RED, check the sidebar for the specific line number.
  3. Use Auto-Fix: If you have "Loose JSON" (like JavaScript objects with single quotes or no quotes on keys), click the Auto Fix button to convert it to strict valid JSON.

Common JSON Errors

1. Trailing Commas

A comma after the last item is invalid.
[1, 2, 3,] → [1, 2, 3]

2. Unquoted Keys

Keys must be wrapped in double quotes.
{ id: 1 } → { "id": 1 }

Frequently Asked Questions

How do I fix JSON errors automatically?▼
Click the 'Auto Fix' button. Our tool attempts to repair common mistakes like trailing commas, single quotes, and unquoted keys.
What does a JSON validator do?▼
It scans your JSON code to ensure it meets the official syntax rules (RFC 8259). It catches errors like missing commas, incorrect quotes, or mismatched brackets.
Is this tool safe for sensitive data?▼
Yes. Validation happens 100% in your browser. No data is sent to any server.
Can I validate large JSON files?▼
Yes. Use the 'Upload JSON' button to validate files without freezing your browser. We support files up to 50MB.

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