01
JSON Validator
Checks whether JSON is valid and reports the exact line, column and reason for the first error…
JSON Formatter
Formats, indents and validates JSON with precise error positions, key sorting and a collapsible tree view.
Developer
Nothing uploaded
No sign-up
Free, unlimited
Paste something on the left to see the result.
In short
JSON Formatter is a free online tool on inputtesthub.com that formats, indents and validates JSON with precise error positions, key sorting and a collapsible tree view. 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 Formatter
- 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 Formatter
The JSON Formatter formats, indents and validates JSON with precise error positions, key sorting and a collapsible tree view. 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
- Reading an API response that arrived as one unbroken line.
- Finding the exact character where a config file breaks.
- Diffing two payloads by formatting both the same way first.
Details
| Error reporting | Line and column number of the first syntax error, with the offending snippet quoted |
|---|---|
| Tolerant mode | Optionally strips // and /* */ comments and trailing commas, which JSONC and many config files use but strict JSON forbids |
| Size handling | Comfortable with several megabytes; everything runs locally so nothing is uploaded |
Frequently asked questions
Is my JSON sent to a server?
No. Parsing and formatting happen in your browser with the built-in JSON engine. Nothing is transmitted, which matters when the payload contains tokens, customer records or anything else you should not be pasting into a remote service.
Why does my JSON fail when it looks fine?
The three usual culprits are a trailing comma before a closing brace, single quotes instead of double quotes around keys or strings, and an unescaped newline inside a string. The error message points at the exact position.
Does the JSON Formatter cost anything?
There is no cost and no cap. The JSON Formatter is not a demo of a paid product, so nothing is held back or watermarked.
Is what I paste into the JSON Formatter stored?
No. The JSON Formatter 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.
Who is the JSON Formatter for?
Typical uses: reading an API response that arrived as one unbroken line. Finding the exact character where a config file breaks. Diffing two payloads by formatting both the same way first. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
What figures does the JSON Formatter work from?
Error reporting is Line and column number of the first syntax error, with the offending snippet quoted. Tolerant mode is Optionally strips // and /* */ comments and trailing commas, which JSONC and many config files use but strict JSON forbids. Size handling is Comfortable with several megabytes; everything runs locally so nothing is uploaded. These are printed on the page itself, so you do not have to take them on trust.
Will this work on a tablet?
Yes. The page is responsive and the tool 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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