JSON Validator
Validate JSON syntax with exact line-and-column error reporting and duplicate-key detection. Client-side only — your data never leaves the browser.
JSON to validate
What this JSON validator does
This JSON validator checks whether a document is valid JSON and reports any problem with an exact line, column, and a plain-English explanation. Paste JSON, and every error is highlighted inline in the editor. Validation runs in your browser — nothing is sent anywhere.
What counts as valid JSON
Whitespace around values is fine, but only the standard four whitespace characters. Newlines, tabs and spaces inside a value are not allowed unless escaped.
Objects must use double-quoted keys and colon-separated key-value pairs.
Strings must be double-quoted; control characters must be escaped.
Numbers must be written in standard decimal form — a leading zero like
01 is invalid.No comments, no trailing commas, no single quotes. These are the most common JSON mistakes, and this validator flags each one at its exact location.