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JSON Validator Online

Validate JSON online with our free JSON Validator. Paste your JSON and instantly check whether it is well-formed, with a clear error message if not.

Paste JSON above and click Validate JSON.

Your JSON is processed directly in your browser and is not uploaded to our servers.

What is a JSON Validator?

A JSON validator checks whether a piece of JSON text follows the JSON specification — matched brackets, correctly quoted keys, no trailing commas, valid value types. It doesn't just format the text; it tells you definitively whether it will parse successfully or point out exactly what's wrong.

Use this free JSON validation tool to check JSON syntax before sending it to an API, saving it to a config file, or debugging a response that's failing to parse. It runs the same JSON parser your browser and most languages use, so a pass here means real parsers will accept it too.

How to Use

How to Validate JSON Online

1

Paste your JSON

Paste the JSON you want to check into the input field above.

2

Click Validate JSON

Click the Validate JSON button to run the check.

3

Read the result

See an instant pass/fail result, with the exact parser error if something is wrong.

4

Fix and re-check

Correct the issue and validate again until you get a clean pass.

Features

JSON Validator Features

Free to use, no signup required
Instant validation in your browser
Clear pass/fail result with parser error details
Shows root type (object, array, etc.) and item count
Works on mobile
Nothing you paste is uploaded to a server
Example

Valid vs Invalid JSON

Valid
{"name":"John","age":30}
Invalid (trailing comma)
{"name":"John","age":30,}

Why Use This JSON Validation Tool?

A single misplaced comma or unclosed bracket can silently break an API integration or a build pipeline. Validating JSON before it reaches production catches these issues in seconds instead of during a confusing runtime error, and doing it in-browser means no data ever leaves your machine.

FAQ

Frequently Asked Questions

Common causes include trailing commas, unquoted keys, single quotes instead of double quotes, unescaped special characters, and mismatched brackets or braces.

Yes — validation is completely free, with no signup and no usage limit.

No — it identifies exactly what is wrong so you can fix it. For automatic formatting of already-valid JSON, use our JSON Formatter.

No. Your JSON is validated directly in your browser using JavaScript and is never uploaded to our servers.

Yes, though very large documents may take a moment longer since validation happens entirely in your browser.

It confirms the JSON is syntactically well-formed using the standard JSON parser. Your API may still apply its own schema or business-logic validation on top of that.
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