JSON Formatter & Validator

Format, minify and validate JSON in your browser.

✓ Free to use✓ No signup✓ Local processing where possible

Format and validate JSON

Pretty-print, minify and validate JSON. Invalid input shows a parsing error.

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Formatting happens in your browser.

Formatting does not change JSON data

Pretty formatting adds whitespace and indentation to make JSON easier to read. Minification removes unnecessary whitespace. Neither operation should change the underlying keys, values or data types when the JSON is valid.

Validation catches syntax, not business rules

A JSON validator can detect structural syntax errors such as missing commas, invalid quotes or malformed arrays. It does not automatically confirm that required application fields are present or that values follow an API schema unless separate schema validation is performed.

Last updated: August 7, 2026

Frequently Asked Questions

Is my JSON sent to the server?

No. The formatter runs in your browser.

Is JSON allowed to use single quotes?

Standard JSON strings and property names use double quotes. Single quotes are common in some programming languages but are not valid JSON syntax.

Does formatting JSON send it to the server?

ToolViso's JSON formatting tool is designed to run in the browser, so the text can be processed locally.

Why use ToolViso?

Free to useNo account is required for the tools on this page.

Transparent inputsYou can see and change the values used to produce the result.

Privacy mindedTools process data locally in your browser where practical.