JSON Validator
Checks JSON syntax only, using the browser's own JSON.parse. For structural checks
against a schema, see the JSON Schema Validator.
About This Tool
JSON Validator checks whether input is syntactically valid JSON using the browser's own
JSON.parse, and when it isn't, reports the exact line and column of the first error. It's
meant as a fast gate before data gets used elsewhere, a quick yes/no with a pointer to the problem.
It only checks syntax, not structure. For malformed JSON, trailing commas, single quotes, unquoted keys, the Auto-Repair button above fixes it inline, or use JSON Repair directly. To check that already-valid data matches a required shape, use JSON Schema Validator.
Key Features
- Line/column error reporting: pinpoints exactly where the first syntax error occurs, when the JSON engine provides a location.
- Auto-Repair shortcut: fixes broken syntax inline and re-validates, without leaving the page.
- File upload & drag-and-drop: validate a
.jsonor.txtfile directly instead of pasting. - Copy or download the result: the validation message exports as plain text.
- Keyboard-driven: Cmd/Ctrl+Enter to validate, Cmd/Ctrl+Shift+C to copy the result.
Example
Invalid JSON with a trailing comma:
{
"a": 1,
} reports the exact line and column of the syntax error where the JSON engine provides one.
FAQ
- Is this the same as schema validation?
- No. This only checks that the text is syntactically valid JSON. Use the JSON Schema Validator to check structure, types, and required fields.
- Does it detect duplicate keys?
- No.
JSON.parsesilently resolves duplicate keys to the last one before this tool ever sees the parsed value, so duplicate-key detection is not claimed. - Is my JSON logged anywhere?
- No. Validation runs with plain JavaScript in your browser tab. Nothing is uploaded or logged.
