How do I validate JSON?

Paste your text above. If parsing succeeds, you see Valid JSON; otherwise you see the error details.

Why is my JSON invalid?

Common causes include trailing commas, single quotes, comments, or missing braces. Strict JSON allows none of those.

What are common JSON syntax errors?

Trailing commas, unquoted property names, single-quoted strings, and NaN/undefined values top the list for beginners.

Can I validate JSON online?

Yes. This free validator works in your browser with no account and no install.

How do I find the line causing a JSON error?

When the browser reports a position, this tool converts it to an approximate line and column so you can jump to the fault.

What is JSON Validator?

A free online tool that checks whether text is valid JSON for students and developers.

How does the JSON Validator work?

It calls JSON.parse in your browser and maps failure positions into line/column hints when available.

How do I use the JSON Validator?

Paste JSON, optionally load a valid or broken example, and read the status panel.

Is this JSON Validator free to use?

Yes. It is free with no sign-up.

Can I use the JSON Validator on mobile?

Yes. Mobile browsers are supported.

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JSON Validator

Validate JSON instantly in your browser. Catch trailing commas, missing quotes, and other syntax errors before they break your app.

Runs in your browser — your data stays on your device

Free tool

Invalid JSON fails silently until parse time. This free JSON validator checks syntax locally so JavaScript developers, frontend engineers, and students can validate API responses and config snippets during coding practice—without installing software.

How to use the JSON Validator

1
Paste the JSON you want to check.
2
Read Valid JSON or the parser error with an approximate line and column.
3
Fix the highlighted issue, then re-paste to confirm.

Why validation belongs next to every API tab

Trailing commas, single quotes, and unquoted keys are the top three classroom mistakes. Catching them here before you paste into production code saves deploy cycles and teaches strict JSON rules that JavaScript object literals do not share.

Invalid JSON example

Tap Broken example to see a trailing comma after true. The validator reports the parse error so you can compare it with the Valid example and learn the difference quickly.

Guides and next steps

Privacy note

JSON validation runs entirely in your browser. We do not upload your payloads.

Frequently asked questions

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