JSON validator with exact error location
Check JSON as you type. Errors are pinned to the exact line and column, with a plain explanation of how to fix them.
🔒 100% Secure & Private: All processing occurs locally within your browser RAM. Your data is never transmitted to any server.
Input JSON
1 line, 0 BPaste JSON here, drop a .json file, or use Load sample.
The result appears here
Paste JSON into the input to start.
Copy and download unlock once the JSON is valid.
Validate JSON and find errors by line and column
The JSON validator checks your input as you type and pinpoints the exact line and column of any syntax error, with a plain-language explanation of what is wrong and how to fix it. The problem is highlighted directly in the editor, and Go to error moves your cursor straight to it.
Browsers report JSON errors very differently, and Safari does not report a position at all. This validator uses the browser's own parser to decide validity and a strict scanner of its own to locate errors, so you get the same precise location in every browser.
The most common JSON errors
- A trailing comma after the last item: {"a": 1,}
- Single quotes instead of double quotes: {'name': 'An'}
- Property names without quotes: {name: "An"}
- Comments, which standard JSON does not allow: // note
- A missing comma between two properties or array items.
- JavaScript values that are not JSON: undefined, NaN or Infinity.
Safe for API keys, tokens and customer data
API responses, config files and database exports often contain access tokens, emails and personal data, and many online formatters send whatever you paste to their servers. This tool runs entirely in your browser: parsing, validation, highlighting and CSV conversion all happen in local memory, and nothing is uploaded or logged. It also handles large files, up to 20 MB, without server-side limits.
Frequently asked questions
Why does JSON not allow trailing commas?
The JSON specification does not allow them, even though JavaScript does. Remove the comma after the last item in the object or array.
Can JSON contain comments?
No. Standard JSON has no comment syntax. Formats such as JSONC and JSON5 allow comments, but files in those formats must be converted before a strict JSON parser can read them.
Why are single quotes invalid in JSON?
JSON requires double quotes around both property names and string values. Replace 'name' with "name".
If this tool says my JSON is valid, is it really valid?
Yes. Validity is decided by the browser's native JSON parser, which follows the official JSON standard (RFC 8259).