JSON Validator & Syntax Checker
Validate JSON syntax online with instant line and column error diagnostics. Verify RFC 8259 compliance and detect malformed JSON tokens in your browser.
How to Use JSON Validator Online
Follow these quick steps to process your data online directly in your browser with zero latency and 100% privacy.
Example Input & Output
Validates JSON syntax against RFC 8259 specifications, confirming quote pairing, bracket closure, and literal type correctness.
{
"project": "DataFormatTools",
"version": "1.0.0",
"isValid": true,
"supportedFormats": [
"JSON",
"YAML",
"XML",
"CSV",
"ENV"
]
}✓ Valid JSON (RFC 8259 Compliant) - Total Keys: 4 - Max Depth: 2 - Document Size: 138 bytes
Common Use Cases
Configuration File Linting
Ensure critical configuration files like package.json, tsconfig.json, or workflow manifests are 100% syntactically valid before committing.
API Request Validation
Verify outgoing request bodies and webhook payloads before triggering cURL or Postman calls.
Specifications & Gotchas
Missing Quotes Around Keys
All object property keys must be wrapped in double quotes.
Unescaped Control Characters
Newlines and tabs inside string literals must be escaped as \n or \t.
Invalid Numeric Formats
Leading zeros (e.g. 0123) and hex notation (0xFF) are invalid in JSON numbers.
Frequently Asked Questions
How do I validate a JSON file online?
Paste your JSON content into the editor; the validator instantly checks syntax and reports any invalid tokens or syntax errors.
What causes JSON syntax errors?
Common causes include single quotes instead of double quotes, trailing commas after the last item, missing colons, and unclosed brackets.
What is the difference between JSON validation and schema validation?
Syntax validation checks if the document obeys RFC 8259 grammar rules, whereas schema validation verifies whether data matches expected fields and types.
Is my validated data stored or logged?
Never. Validation runs purely on your client device in memory.
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