01
JSON Formatter
Formats, indents and validates JSON with precise error positions, key sorting and a…
JSON Validator
Checks whether JSON is valid and reports the exact line, column and reason for the first error found.
Developer
Nothing uploaded
No sign-up
Free, unlimited
Paste something on the left to see the result.
In short
JSON Validator is a free online tool on inputtesthub.com that checks whether JSON is valid and reports the exact line, column and reason for the first error found. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.
How to use the JSON Validator
- Paste your code into the input area.
- Choose the indentation and output options you want.
- Read the formatted result, then copy or download it.
About the JSON Validator
The JSON Validator checks whether JSON is valid and reports the exact line, column and reason for the first error found. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Checking a config file before deploying it.
- Verifying an API payload matches JSON spec.
- Finding a syntax error in a large document quickly.
Frequently asked questions
Are there any usage caps on the JSON Validator?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the utility.
Is my data uploaded anywhere?
No. The JSON Validator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
When would I actually need the JSON Validator?
In practice it gets used for three things: checking a config file before deploying it. Verifying an API payload matches JSON spec. Finding a syntax error in a large document quickly. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there an app version?
Yes. The page is responsive and the utility works in Chrome, Safari, Firefox, Edge and Samsung Internet on both Android and iOS. There is no app to install and nothing to sign into.
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