Developer Tools

JSON Validator

Paste JSON and get a precise validity report in milliseconds. If valid, a green badge confirms it. If invalid, you get the exact line and column of the error plus a human-readable explanation. No vague 'unexpected token' messages.

Catches syntax errors with line info Browser-only, no upload Instant validation
json JSON to validate
Runs in your browser; code never leaves your device

Features

  • Validates JSON and shows exact error line and column
  • Human-readable error messages (not just 'Unexpected token')
  • Valid JSON gets a detailed summary: depth, key count, type
  • Highlights the specific problem location
  • Copy or download the validated JSON after formatting
  • Strict RFC 8259 compliance checking

How to use it

  1. Paste your JSON into the input panel.
  2. The validator runs instantly and shows Valid or Error.
  3. For errors, read the exact location and message to fix the issue.
  4. For valid JSON, review the structure summary and copy the formatted output.

Use cases

  • Debugging JSON payloads that cause API parse errors
  • Validating handwritten JSON config files before deployment
  • Checking AI-generated JSON for syntax mistakes
  • Verifying JSON serialization output from code

Limitations

  • The validator checks syntax only; it does not validate against a schema.
  • Very large input can be slower on older devices.
  • This utility is designed for common snippets and local inspection, not as a full security or language-specific validator.
See also

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Questions & answers

Frequently asked

Why do I get 'unexpected token' errors in other tools but clearer messages here?

This validator parses incrementally and maps byte offsets to line/column, then translates each error code into a plain English description.

Does it validate against a JSON Schema?

Not yet. This tool checks syntax only. Use JSON to JSON Schema to generate a schema, then validate separately.