JSON Validator - Check JSON Syntax Online
Paste JSON to instantly check whether it's syntactically valid, with the exact parser error message shown when it isn't.
Paste JSON to Validate
Free JSON Validator — Check JSON Syntax Online
Paste any JSON string to instantly check whether it's syntactically valid. If it isn't, the exact error message from the parser is shown so you can find and fix the problem quickly.
How to Use It
Paste your JSON into the box above. Validation happens live as you type or paste — a green "Valid JSON" badge means the syntax checks out, while a red "Invalid JSON" badge shows the specific parser error message beneath the editor.
Example
Pasting {"name": "Alice", "age": 30} shows a "Valid JSON" badge. Removing the closing brace or leaving a trailing comma instead produces an "Invalid JSON" badge along with the browser's exact syntax error message, such as "Unexpected end of JSON input".
Common Use Cases
- Checking whether an API response or request body is well-formed before debugging further.
- Validating a config file or `.json` snippet before committing it.
- Quickly confirming JSON pasted from a chat, email, or log file isn't corrupted.
FAQs
Does it tell me the exact line or column of the error?
The tool displays the exact error message your browser's JSON parser produces, as-is. Modern browsers often include a position (and sometimes a line/column) directly in that message — but this isn't guaranteed for every syntax error, since JavaScript's built-in JSON parser doesn't formally expose structured line/column data.
What counts as "invalid" JSON?
Anything that fails strict JSON syntax — trailing commas, single quotes instead of double quotes, unquoted keys, comments, or missing brackets/braces are all common causes, since JSON is stricter than JavaScript object literal syntax.
Is my data uploaded anywhere?
No — validation runs entirely in your browser using the built-in JSON parser. Nothing you paste is sent to a server.