JSON Validator
Make sure your JSON is valid before you deploy or share it. Paste content, validate instantly, and get feedback you can act on. Great for quick QA.
JSON Validator
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Result will appear here...
SIMILAR TOOLS
What this does
So your app refuses to start, or an API keeps rejecting your request, and the culprit is a single stray character buried in a wall of JSON. This finds it. Paste your JSON or upload a .json file, press Validate, and it tells you whether the JSON is well formed. If it is not, it points you at what went wrong.
How to use it
- Paste the JSON into the box, or upload a
.jsonfile. - Press Validate.
- Read the verdict. Either it confirms the JSON is valid, or it shows an error describing the problem.
How it works
Behind the button is a JSON parser called jsonlint. It tries to read your text as JSON, and if it cannot, it does not just shrug and say invalid, it reports where the parsing broke and what it expected at that point. That is the useful difference between a real validator and a plain pass or fail check, because the message usually leads you straight to the offending spot. The whole thing runs in your browser, so your JSON stays on your device and nothing is uploaded.
What usually breaks JSON
When the validator rejects something, the cause is nearly always small and mechanical. A few of the usual suspects:
- A missing comma between two items, or one comma too many sitting after the last item.
- A key or string wrapped in single quotes, when JSON only recognises double quotes.
- A bracket or brace that was opened and never closed, or closed in the wrong order.
- A comment carried over from a config file, which JSON has no concept of.
The error message points at the area, so once you know where to look the fix is usually a matter of seconds.
Valid is not the same as correct
One thing worth knowing: this checks whether your JSON is built correctly, not whether it contains the right information for your particular use. JSON can be perfectly valid and still be missing a field your program needs, or hold a number where you expected text. Validity here means the structure follows the JSON grammar. Confirming that the contents match what your application expects is a separate job, usually handled with a schema.
Questions people ask
What does valid actually mean?
It means the text follows the JSON grammar correctly, with the brackets, quotes, commas, and colons all where they belong. It does not judge whether the data itself is right for your purpose.
Does it check my JSON against a schema?
No. It checks the syntax only. Verifying that the fields and their types match what your application needs is a separate step.
Why does it mention a position in the text?
The jsonlint parser keeps track of where it is as it reads, so when it meets something unexpected it can tell you roughly where the trouble sits, which saves a lot of hunting.
Is my JSON sent anywhere?
No. The check happens entirely in your browser, so nothing you paste or upload leaves your machine.
References
- Ecma International. ECMA-404: The JSON Data Interchange Syntax. https://ecma-international.org/publications-and-standards/standards/ecma-404/
- Internet Engineering Task Force. RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format. https://www.rfc-editor.org/rfc/rfc8259
- MDN Web Docs. JSON.parse(). https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
Sugam Baskota is a senior software engineer and Computer Science graduate from UT Arlington, with interests in user scripts, browser extensions, developer tooling, and productivity systems. He spends time building practical utilities and extensions in the kinds of workflows Eon is designed to simplify. At Eon Tools, he reviews useful, password, and developer tools.