JSON Validator

Check if your JSON is valid, find the exact error, and fix it fast. Free, private, and runs entirely in your browser.

Validate JSON Now

Paste your JSON to validate

Paste any JSON. The validator checks syntax and reports errors with location. Max size: 10 MB.

Awaiting input — paste JSON and click Validate.

How JSON Validator Works

Three steps to know if your JSON is valid.

Paste JSON

Paste any JSON string — from an API, config file, or log — into the input area. It does not need to be formatted nicely.

Click Validate

Press "Validate JSON." The tool parses your input and instantly reports whether it is valid or shows the exact error and position.

Format if Valid

If valid, optionally format your JSON into a readable, indented structure with one click.

Features of JSON Validator

Clear validation, friendly errors, and a formatting bonus.

Instant Validation

Find out in milliseconds whether your JSON is valid, without leaving your browser.

Precise Error Location

When validation fails, the tool shows the exact position and a readable description of what went wrong.

Format Valid JSON

Valid JSON can be beautified and indented directly, saving you a trip to a separate formatter.

100% Private

Validation happens locally. Your JSON is never sent to or stored on any server.

Works Anywhere

Runs on any device with a modern browser — desktop, tablet, or phone. Free, no signup.

Fast and Lightweight

This validator loads instantly and uses almost no resources, even for large JSON payloads up to 10 MB.

What Is JSON Validator?

A JSON validator is a tool that checks whether a given string is well-formed, valid JSON. Unlike many formats, JSON has strict syntax rules — every bracket must be matched, every string must be quoted, and commas must be placed correctly. A single missing comma or an unquoted key can make an entire API response fail to parse.

This free online JSON validator immediately tells you whether your JSON is valid. If it is not, it shows you exactly where the problem is and explains it in plain language, so you can fix it quickly rather than hunting through lines of data. If your JSON is valid, you can format it into a clean, indented structure with a single click.

Everything runs locally in your browser, so you can safely validate private or sensitive JSON without uploading it anywhere. Whether you are a developer debugging a fetch response, a data analyst validating an export, or anyone working with JSON from an API, this tool is fast, free, and available on any device.

Frequently Asked Questions

What does it mean for JSON to be "valid"?

Valid JSON means the text follows the JSON specification exactly: keys and strings in double quotes, correct commas and colons, matched brackets and braces, and no trailing commas. If any rule is broken, the parser treats it as invalid.

Why is my JSON showing as invalid?

Common causes include missing or extra commas, single quotes instead of double quotes, trailing commas, unquoted keys, or a missing closing bracket. The validator shows the exact error location to help you fix it.

Is this JSON validator free?

Yes, it is completely free with no signup or usage limits.

Is my JSON kept private when I validate it?

Yes. Validation happens entirely in your browser and your JSON is never uploaded or stored anywhere.