Sumplain

Developer tool

JSON Formatter

Format, validate, and minify JSON safely in your browser.

Input

JSON editor

Output

Formatted JSON

Format valid JSON to see the result here.

Your text is processed locally in this browser.

Format JSON without losing clarity

Formatted JSON makes nested data easier to inspect, review, and share. This tool validates the text first, then applies consistent indentation. Use minify when you need compact JSON for a request or configuration value.

Check errors before sharing

Invalid JSON commonly comes from missing commas, unmatched braces, unquoted keys, or trailing commas. The error message is shown directly below the editor so you can correct the input without losing your place.

Your data stays in the browser

Formatting happens on this page. Still, avoid pasting credentials, tokens, or production secrets into any shared environment. Redact sensitive values before using data in a bug report or documentation.

Frequently asked questions

A few quick answers before you go.

Does this tool send my JSON anywhere?

No. Formatting and validation happen locally in your browser.

What makes JSON valid?

JSON needs quoted property names and strings, matching brackets, and no trailing commas.

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Disclaimer: This tool is for general information only and does not provide financial, medical, or professional advice.