This validator parses your JSON with the same rules a server or browser applies, then reports either a clean pass or the precise position where parsing stopped. Three mistakes account for most failures: a trailing comma before a closing brace, single quotes instead of double, and unquoted object keys — all of them legal in JavaScript object literals and all of them invalid in JSON, which is why code copied out of a JS file so often refuses to parse. The tool also confirms structural details people miss, such as JSON allowing only double-quoted strings, no comments, and no NaN or Infinity values.
Free, fast, and runs entirely in your browser — no signup, no upload to a server.