JSON Validator
Validate JSON syntax and structure with detailed error reporting
Examples & Usage
Valid JSON
A properly formatted JSON object
{
"name": "John Doe",
"age": 30,
"city": "New York",
"hobbies": ["reading", "swimming", "coding"],
"address": {
"street": "123 Main St",
"zip": "10001"
}
}Invalid JSON
JSON with syntax errors
{
"name": "John Doe",
"age": 30,
"city": "New York",
"hobbies": ["reading", "swimming", "coding"
"address": {
"street": "123 Main St",
"zip": "10001"
}
}✅ Local Processing - Data Never Leaves Your Browser
よくある質問
What is a JSON Validator?
An online tool that checks whether JSON complies with standard syntax (RFC 8259 / ECMA-404), pinpoints errors, and explains causes so you can fix them quickly.
What can JSON Validator do?
Validate JSON, beautify and minify, optional tree view, fix common issues, convert to CSV/XML/YAML, and process locally without uploading data.
How do I use JSON Validator?
Paste or upload a .json file, the tool validates instantly and shows formatted output. Errors are highlighted with line and column numbers.
Can I upload a JSON file?
Yes. Click Upload to select a .json file and we will validate it locally in your browser.
Can it validate and format automatically?
Yes. With real-time updates enabled, input is validated and formatted as you type.
Can I download the validated JSON?
Yes. Click Download to save the formatted (or fixed) JSON file.
How are errors displayed?
Errors include line and column numbers, a description (e.g., Unexpected token, Missing comma), and the problematic area is highlighted.
Can it auto-fix JSON errors?
Some common issues can be fixed automatically, such as missing/incorrect quotes, unescaped characters, trailing commas, comments, and wrong boolean/null casing.
Is my data uploaded?
No. All processing happens locally in your browser. Nothing leaves your device.
Which standards does it follow?
RFC 8259 and ECMA-404 for JSON syntax and data interchange.
Why validate JSON?
Validation catches syntax mistakes, invalid escapes, and structural issues early to prevent runtime errors.
Why is JSON often preferred over XML?
JSON is lighter, easier to read and parse, and maps naturally to JavaScript objects, so it’s widely used for APIs.
What extra features are available?
Beautifier, Minifier, Editor, Tree Viewer, JSON→CSV/XML/YAML converters, and an auto-fixer.
Can I change indentation and display?
Yes. Choose 1–10 spaces and control pretty/compact formatting and tree expansion.
Which data types does JSON support?
String, Number, Boolean, Array, Object, and Null.
Can it validate JSON from a URL?
Yes. Provide a URL and the tool can fetch the content and validate it.
Can I validate large JSON files?
Yes. Large files are handled efficiently and locally; there are no server-side limits.
What's the difference between warnings and errors?
Errors prevent your JSON from being valid and must be fixed. Warnings indicate potential issues or best practices that should be considered but don't break validity.
What does JSON validation check?
JSON validation checks your data for syntax errors, structural issues, and compliance with JSON standards to ensure your data is properly formatted and valid.