Developer Tools
JSON Validator
Validate JSON syntax online with instant syntax error messages, line details, and a fullscreen editor for long API payloads or config files.
1 line • 0 chars
Paste any JSON payload, API response, or config snippet to validate the syntax before formatting or schema checks.
Quick examples
Usage notes
- Common JSON errors: trailing commas, single quotes, unquoted keys.
- JSON requires double quotes for all property names and string values. Bare keys are JavaScript object syntax, not standard JSON.
- Open the editor in fullscreen mode when you need to inspect large API responses or nested objects.
- Use our JSON Formatter tool to auto-fix and beautify valid JSON.
Related pages
How to Use This Tool
- 1Paste your JSON into the text area.
- 2Click Validate JSON to check if the syntax is correct.
- 3If valid, you'll see a green success message. If invalid, the error message explains what went wrong, where it happened, and when the input is JavaScript object syntax instead of standard JSON.
Frequently Asked Questions
- What makes JSON invalid?
- Common issues include trailing commas, single quotes, unquoted keys, comments (JSON doesn't support comments), and mismatched brackets or braces. Unquoted keys are valid in JavaScript object literals and JSON5, but not in standard JSON.
- How is this different from JSON Formatter?
- JSON Validator only checks if your JSON is syntactically correct and tells you where errors are. JSON Formatter also beautifies valid JSON with indentation. Use Validator for quick checks, Formatter for cleanup.
- Can I validate JSON Schema?
- Use our JSON Schema Validator when you need to validate structure, required fields, and value rules against a schema. This tool checks syntax only.
- Is my data sent to a server?
- No. Validation happens entirely in your browser. Your data stays on your device.