JSON Validator
Validate, lint, and fix your JSON data instantly.
Locate syntax errors with precise line numbers.
Valid JSON
The syntax is correct. Your data is good to go.
Common Use Cases
Debug API Configs
Verify POST bodies and API responses are valid JSON before integration.
Config Files
Check package.json or VS Code settings for syntax errors.
Find Typo
Locate missing commas, unclosed brackets, or smart quotes that break parsing.
Linting
Ensure strict adherence to JSON standards for cross-platform compatibility.
Why use a JSON Validator?
JSON (JavaScript Object Notation) is strict. A single missing comma or trailing comma can break your application or crash your server. This tool helps you:
- Debug API Responses: Paste the payload to ensure it's valid before using it in your frontend application.
- Find Typos: Quickly locate unclosed quotes, missing brackets, or invalid characters.
- Validate Schema: Ensure your data structure matches what your application expects.
Validating JSON in Code
How to safely parse and validate JSON strings in your applications.
const jsonString = '{"name": "Alice"}';
try {
const data = JSON.parse(jsonString);
console.log("Valid JSON:", data);
} catch (error) {
// Catch syntax errors
console.error("Invalid JSON:", error.message);
}import json
data = '{"name": "Alice"}'
try:
parsed = json.loads(data)
print("Valid")
except json.JSONDecodeError as e:
print(f"Invalid JSON at line {e.lineno}: {e.msg}")$json = '{"name": "Alice"}';
$obj = json_decode($json);
if (json_last_error() === JSON_ERROR_NONE) {
echo "Valid";
} else {
echo "Error: " . json_last_error_msg();
}import "encoding/json"
func isValid(s string) bool {
var js map[string]interface{}
// Unmarshal returns error if JSON is invalid
return json.Unmarshal([]byte(s), &js) == nil
}Frequently Asked Questions
What is the most common JSON syntax error?
The most common errors are trailing commas (e.g. {"a":1,}), missing quotes around keys, and using single quotes instead of double quotes.
Why is trailing comma invalid?
The JSON specification (based on older JS versions) strictly forbids trailing commas. While modern JS allows them, strict JSON parsers will fail.
Can I use comments in JSON?
No. Standard JSON does not support comments. If you need comments, consider using JSONC (JSON with Comments) or YAML for configuration files.
Is my data secure?
Yes. Validation is performed locally in your browser using JSON.parse(). No data is sent to our servers.
What is the difference between null and undefined?
JSON supports null as a value, but not undefined. Keys with undefined values are typically omitted during stringification.
How do I format/beautify JSON?
Use our related JSON Formatter tool. This validator focuses on finding errors, while the formatter makes valid JSON readable.