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JSON Validator

Validate your JSON data online. Check for syntax errors and ensure your JSON is well-formed.

How to Use JSON Validator

1

Paste your JSON data

Copy your JSON from an API response, config file, or any source and paste it into the validator input area.

2

Review validation results

The validator instantly checks syntax and displays errors with exact line numbers and descriptive messages explaining what went wrong.

3

Fix errors and re-validate

Use the error messages to locate and fix issues like missing commas, unmatched brackets, or invalid values. The validator re-checks automatically.

4

Copy your valid JSON

Once validation passes, copy your clean, verified JSON for use in your application, API, or configuration.

About JSON Validator

Validate JSON online for free with our JSON Validator and syntax checker. Paste your JSON data and instantly check for syntax errors, missing commas, unmatched brackets, invalid strings, and structural issues. The validator pinpoints exact line numbers and positions of every error, making it easy to debug API responses, configuration files, package.json, and database exports. Handles large JSON documents efficiently. All validation runs in your browser — your data never leaves your device.

Key Features

  • Validate JSON syntax instantly with detailed, descriptive error messages
  • Pinpoint exact line number and character position of every error
  • Support for large JSON documents with fast browser-based parsing
  • Instant real-time validation as you paste or type JSON data
  • Check nested objects, arrays, and complex JSON structures
  • Free online JSON lint tool — no signup, no limits, 100% private

Frequently Asked Questions

How to validate JSON online for free?▾
Paste your JSON into the validator and it instantly checks for syntax errors. Any issues are highlighted with exact line numbers and clear error messages. No signup or payment required.
How to check if JSON is valid?▾
Valid JSON must have properly matched brackets and braces, quoted string keys, correct comma placement, and valid data types. Our validator checks all these rules instantly.
What does JSON validation check?▾
It checks for correct syntax including proper brackets, commas, quoted keys, valid string escaping, correct nesting of objects and arrays, and data types according to the JSON specification (RFC 8259).
How to find errors in JSON?▾
The validator highlights each error with the exact line number and character position, plus a descriptive message like "Expected comma" or "Unexpected token". This makes locating and fixing issues quick and easy.
Can this tool fix invalid JSON automatically?▾
The validator identifies errors and their exact locations so you can fix them manually. Automatic fixing is not supported because JSON errors often require understanding the intended data structure.
Is this JSON validator safe and private?▾
Yes. All validation happens entirely in your browser using JavaScript. Your JSON data is never sent to any server, making it safe for API keys, credentials, and sensitive configuration data.
Can it validate large JSON files?▾
Yes. The validator handles large JSON documents efficiently in the browser. Files up to several megabytes are processed quickly, though very large files may depend on your device performance.
What is JSON lint?▾
JSON lint (or JSONLint) is the process of checking JSON data for syntax errors. Our tool functions as a free online JSON linter that validates your data against the JSON specification.