What common mistakes cause invalid JSON?

Trailing commas, single quotes instead of double quotes, and unquoted keys are the most common causes.

Is my JSON data uploaded anywhere?

No — validation uses your browser's native JSON parser and never sends data to a server.

Does this tell me exactly which character is wrong?

The error message comes directly from the browser's JSON parser, which typically includes a position or context clue.

Can I validate JSON with comments in it?

No — standard JSON does not support comments; a JSON-with-comments (JSONC) file would need comments removed first.

Does root type matter?

Valid JSON can have any value type — object, array, string, number, boolean or null — as its root; the validator reports whichever type yours has.

Is empty text valid JSON?

No — an empty string is not valid JSON; you'll see an error until at least a minimal valid value (like {} or []) is entered.

JSON & Code Tools

JSON Validator

Paste JSON to instantly check whether it is valid, with a clear error message if it is not.

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Runs in Your Browser
Instant Results
100% Private

Your Text

Your result will appear here.

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What Is a JSON Validator?

A JSON validator checks whether a block of text is syntactically valid JSON — correctly matched brackets and quotes, properly comma-separated values, no trailing commas — and reports exactly what's wrong if it isn't.

It's the fastest way to confirm a hand-edited config file or a suspicious API response is actually parseable, before spending time debugging code that assumes it is.

Who Uses This Tool?

For Business

Confirm an API response or webhook payload is valid before integrating it.

For Personal Use

Check a hand-edited config file for typos.

For Students

Learn what makes JSON valid or invalid for a course assignment.

For Offices

Validate a data export before importing it into another system.

Why Use This Tool

Key Features

Clear Pass/Fail Result

Instantly see whether your JSON is valid.

Root Type & Size

See the root type (object/array) and its size at a glance.

Instant Validation

Results update immediately as you paste or edit.

100% Private

Your data is never uploaded — validation happens entirely in your browser.

The Payoff

Benefits

Pinpoint Errors Fast

Get a specific error message instead of guessing what's wrong.

Quick Sanity Check

Confirm valid JSON before pasting it into code or a config file.

Nothing Uploaded

Safe for sensitive data, since nothing leaves your browser.

Step by Step

How to Use JSON Validator

Paste Your JSON

Add the JSON you want to check.

Read the Result

See instantly whether it's valid, with details if not.

Fix and Re-Check

Correct any reported issue and check again.

Specifications

Technical Details

Detail	Value
Input	Any text, checked against strict JSON syntax rules
Processing	No practical limit — handled entirely by your browser
Output	Uses the native JSON parser for spec-accurate validation

You Can Verify This

Privacy & Security

What actually happens to your file when you use this tool.

100% Client-Side

This tool runs entirely inside your browser using JavaScript — nothing you type or generate is ever sent anywhere.

No Upload, Ever

There is no file upload and no server processing step — your data never leaves your device.

Works Offline

Once this page has loaded, the tool keeps working even without an internet connection.

Nothing Stored

Nothing you enter is saved on our servers — refreshing the page clears everything.

No Tracking of Your Input

We have no way to see what you type, generate or convert with this tool.

Get Better Results

Tips

Watch for Trailing Commas

A trailing comma after the last item in an object or array is a common cause of invalid JSON.

Use Double Quotes Only

JSON requires double quotes for strings and keys — single quotes are invalid.

Frequently Asked Questions