>Fafa Dev Tools

JSON Validator

Validate JSON syntax with detailed error reporting including line and column numbers. Free online JSON validator with instant feedback and structure analysis.

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Paste JSON in the left panel to validate

What is JSON Validator?

A JSON validator checks whether a JSON string conforms to the JSON specification (RFC 8259). It detects syntax errors like missing commas, trailing commas, unquoted keys, single quotes instead of double quotes, and unclosed brackets. This validator provides precise error locations with line and column numbers so you can fix issues quickly.

How to Use

  1. Paste your JSON data into the input area
  2. The validator checks syntax instantly and displays the result
  3. If valid, you'll see the JSON type, key count, depth, and size
  4. If invalid, the exact error location (line and column) is shown with a description

Examples

Valid JSON object

Input{"name":"Alice","age":30,"active":true}
OutputValid JSON Type: Object | Keys: 3 | Depth: 1 | Size: 41 bytes

Invalid JSON (trailing comma)

Input{"name":"Alice",}
OutputInvalid JSON — Unexpected comma at position 15 Line 1, Column 16

Frequently Asked Questions

What JSON errors does this detect?

It detects all syntax errors: missing or extra commas, trailing commas, unquoted keys, single quotes, unclosed brackets/braces, invalid escape sequences, unexpected tokens, and incomplete/truncated JSON. Each error includes line and column position.

Does it validate JSON against a schema?

No. This tool validates JSON syntax (structure and format), not JSON Schema. It checks that your JSON is well-formed according to RFC 8259 but does not validate data types, required fields, or value constraints.

What's the difference between JSON validation and JSON formatting?

Validation checks if JSON is syntactically correct and reports errors. Formatting (pretty-printing) takes valid JSON and reformats it with indentation for readability. Use validation first to fix errors, then formatting to make it readable.