JSON Validator
How to Use
Paste or type JSON into the input area. The validator checks syntax in real time and shows whether the JSON is valid. If there's an error, it displays the error message and position. Valid JSON is automatically formatted with proper indentation below.
What Is JSON?
JSON (JavaScript Object Notation) is a lightweight data format used for exchanging data between systems. It supports objects (key-value pairs in curly braces), arrays (ordered lists in square brackets), strings, numbers, booleans, and null. JSON requires double quotes for strings, no trailing commas, and no comments.
Common Use Cases
- Debugging API responses that return malformed JSON.
- Validating configuration files (package.json, tsconfig.json, etc.).
- Checking JSON data before importing into databases.
- Verifying webhook payloads from external services.
- Cleaning up and formatting minified JSON for readability.
Tips
- Common JSON errors: trailing commas, single quotes, unquoted keys, missing closing brackets.
- JSON does not support comments — remove // or /* */ before validating.
- Use the formatted output to spot structural issues in deeply nested data.
- The key/value/depth stats help you understand the complexity of your data.
- For large JSON files, paste a subset first to isolate the error location.
Privacy
All JSON validation happens in your browser. No data is sent to any server.
FAQ
What is the difference between validating JSON and validating against a JSON Schema?
This tool checks syntax — that the JSON parses correctly and follows the spec. JSON Schema validation is separate: it checks the data against rules for required fields, types, and ranges. Here you get syntax checking plus key, value, and depth counts, not schema rules.
Is it safe to paste JSON that contains private or sensitive data?
Yes. All validation and formatting run entirely in your browser — nothing is uploaded, logged, or stored. You can safely check payloads containing tokens or personal information.
Why does my JSON with comments or trailing commas fail?
Strict JSON forbids comments (// and /* */) and trailing commas after the last item. The validator flags these and gives a targeted hint, but you must remove them — JSON5 or JSONC syntax is not accepted.
Does it tell me exactly where the error is?
Yes. When parsing fails it reports the line and column of the problem, and for common mistakes like trailing commas, single quotes, or unquoted keys it adds a specific hint on how to fix it.
Can it handle very large JSON files?
It validates in your browser, so extremely large inputs depend on your device's memory. If a big file is hard to debug, paste a smaller subset first to isolate the error location.