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JSON validator with error line numbers

This page exists for one moment: you have broken JSON and no idea where. Paste it in and the parser points at the exact line and column of the first problem, in plain English rather than a raw character offset — the same formatter and minifier from our main JSON tool are here too, once the error is fixed.

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  • Works offline once loaded
  • Free forever, no signup
Formatted

Valid JSON.

  • Keys {{ stats.keys }}
  • Depth {{ stats.depth }}
  • Minified {{ stats.minified }} chars
  • Saved {{ stats.saved }}%

How to use this tool

  1. Paste the JSON that is failing

    Straight from your API response, config file or code editor.

  2. Read the error banner

    It names the line and column of the first syntax problem, not just a character offset.

  3. Fix and re-check

    The banner disappears and turns into a green "Valid JSON" the moment the syntax is clean.

Questions people ask

Why do I get "Unexpected token" instead of a clear reason?

That is JavaScript's own parser message — this tool improves it by adding the line and column, but the underlying cause is still one of a handful of things: a trailing comma, single quotes, an unquoted key, or a stray comment. All four are invalid JSON even though they are valid JavaScript.

My JSON looks fine to my eyes — what am I missing?

The two most common invisible culprits are a trailing comma after the very last item in an object or array, and smart/curly quotes (" ") pasted in from a word processor instead of straight double quotes. Both parse as errors even though they look identical at a glance.

Does this validate against a schema, like required fields?

No — this checks only that the text is syntactically valid JSON, not that it matches any particular shape your application expects. Schema validation (JSON Schema) is a separate, much larger problem this tool does not attempt.

Can I also format or minify from here?

Yes — once your JSON parses, the same Format and Minify buttons from our main JSON formatter are right there, so there is no need to jump to a second page.

Is anything I paste here sent to a server?

No. The whole tool is JavaScript running in your browser, and this site has no endpoint that accepts text. That matters when what you are pasting is a real API payload, a customer record, or a password.

Related tools

Bookmark this page — the tool keeps working offline, and your settings stay in this browser. Built by Dynamb Technologies, who make software for a living.