Browser-based developer tools

JSON Formatter

Beautify, validate, minify and inspect JSON without sending input to a backend.

Local-first tools: formatting, validation and parsing run in your browser for this static release.

Input

0 bytes

Result

Ready

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Reference notes

Clean JSON for everyday development

Local-first by default

Formalint keeps formatting work inside the browser for this static release. That makes it suitable for API payloads, sample responses, configuration drafts and quick debugging sessions.

Readable structure

The tree view helps compare objects, arrays, keys, values and nesting depth when a raw API response is too dense to scan comfortably.

Search-friendly utility

This page is intentionally focused on one developer task, with fast loading, no external UI libraries and clear navigation to related tools.

Frequently asked

JSON formatter questions

Is the Formalint JSON formatter private?

The static Formalint formatter processes JSON in the browser. The current version does not upload pasted JSON to a server.

Can Formalint validate invalid JSON?

Formalint parses JSON with the browser runtime and reports validation errors so developers can fix malformed input. The most common causes are trailing commas, single quotes instead of double quotes, and unescaped control characters.

Does Formalint support minified JSON?

Yes. Formalint can minify valid JSON and can also reformat minified JSON into readable indentation.

Can I convert JSON to a tree view for large payloads?

Yes. The tree view collapses nested objects and arrays so you can inspect a large API response or config file without scrolling through flat text.

Does the formatter support JSON5 or comments?

No, this tool validates strict JSON per the JSON specification. Comments and trailing commas are treated as syntax errors, matching how most APIs and parsers behave in production.