DevToolsKit

JSON Validator

Free

Validate JSON syntax with detailed error messages and line numbers.

Runs 100% in your browser — data stays private
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About JSON Validator

Quickly validate JSON syntax with our free online JSON Validator. Get instant feedback on whether your JSON is valid, along with detailed error messages and line numbers when something is wrong.

Essential for developers working with APIs, config files, and data pipelines. Paste your JSON and validation runs automatically — no button clicks needed.

All validation is performed client-side in your browser, keeping your data completely private and secure.

Key Features

  • Real-time JSON syntax validation
  • Detailed error messages with line and column numbers
  • Detects arrays vs objects and item counts
  • Instant feedback as you type
  • No data sent to any server

How to Use

  1. 1Paste your JSON into the input area.
  2. 2Validation runs automatically.
  3. 3Green badge means valid; red badge shows the exact error.
  4. 4Fix errors using the line/column info provided.

Common Use Cases

Validating API request/response bodies
Checking config files before deployment
Debugging JSON from log files
Verifying exported database records

Frequently Asked Questions

How does the JSON validator detect errors?+

It uses the browser's native JSON parser. Any syntax error triggers a detailed message with approximate line and column position.

Can I validate large JSON files?+

Yes, but very large files (10MB+) may slow your browser since processing is client-side.

Does it validate JSON schema?+

This tool validates JSON syntax only. For schema validation, use a dedicated JSON Schema validator.

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