JSON Formatter Online - Free & Local

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What is JSON Formatter?

JSON Formatter is a free ComTools utility that beautify json with configurable indentation. Data is processed locally in your browser; nothing is uploaded.

Features

Free to use
No signup required
Local processing
Data is processed locally in your browser; nothing is uploaded.
Bilingual UI
Chinese and English supported
Developer friendly
Beautify JSON with configurable indentation

Use cases

Daily development
Data conversion
Learning and demos
Quick format checks

How to use

Open the tool page
Enter or upload your data
Click the action button
Copy or download the result

FAQ

QIs my data uploaded?

Data is processed locally in your browser; nothing is uploaded.

QIs it free?

Yes, completely free with no usage limits.

QWhich browsers are supported?

Modern browsers: Chrome, Edge, Firefox, Safari.

QHow to report issues?

Use the Messages page for feedback or custom requests.

JSON formatting guide

JSON formatting turns compact JSON into indented, readable text for debugging APIs and config files. In C#, use System.Text.Json or Newtonsoft.Json.

// System.Text.Json
var json = JsonSerializer.Serialize(obj, new JsonSerializerOptions { WriteIndented = true });

// Newtonsoft.Json
var formatted = JsonConvert.SerializeObject(obj, Formatting.Indented);