DevKit4You/JSON Formatter

JSON Formatter

Validate, pretty-print with syntax highlighting, minify, and sort JSON keys. Error messages show exact line and column numbers.

Indent
JSON Input
0 chars
Validation
Strict RFC 8259. Error messages show exact line and column numbers.
🎨
Syntax Highlighting
Keys, strings, numbers, booleans and null values are colour-coded.
🗜️
Minify
Strip all whitespace for compact transmission or storage in one click.
🔤
Sort Keys
Alphabetically sort all object keys recursively for consistent diffs.

JSON Formatter & Validator

JSON Formatter and JSON Validator help to auto-format JSON and validate your JSON text. It also provides syntax highlighting that helps you navigate and read formatted JSON data at a glance.

It helps to validate JSON online with descriptive error messages. It's also a JSON Beautifier that supports multiple indentation levels: 2 spaces, 3 spaces, and 4 spaces — as well as tab indentation.

Features

Validation with Error Messages

Validates JSON online against RFC 8259 specifications. When your JSON contains a syntax error, the error message pinpoints the exact location so you can fix it instantly — no guesswork required.

JSON File Formatter

Provides functionality to upload a JSON file and download the formatted result. This makes it easy to beautify JSON files from your local filesystem without any software installation.

API Response Formatter

95% of APIs use JSON to transfer data between client and server. This tool works as an API response formatter — paste any raw API response and instantly get a human-readable, indented view.

Sort Keys Alphabetically

Recursively sorts all object keys in alphabetical order. Consistent key ordering makes JSON diffs cleaner and easier to review in version control.

Minify JSON

Strips all whitespace and newlines to produce the most compact valid JSON string — ideal for reducing payload size in network requests or storage.

Auto-Format on Paste

Toggle auto-format to instantly beautify JSON as soon as you paste it. Use it as a JSON notepad — a lightweight alternative to VS Code or Sublime for quick JSON inspection and cleanup.

Cross-Platform & Zero Setup

Works entirely in your browser. No installation, no account, no server-side processing. Compatible with Windows, Mac, Linux, Chrome, Firefox, Safari, and Edge.

JSON Example

Below is a sample JSON object showing common data types. Paste it into the formatter above to see syntax highlighting in action:

{ "InsuranceCompanies": { "Top Insurance Companies": [ { "No": "1", "Name": "Berkshire Hathaway (BRK.A)", "Market Capitalization": "$308 billion" } ], "source": "investopedia.com", "time": "Feb 2019" } }

What Is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It is built on two universal data structures: a collection of name/value pairs (objects) and an ordered list of values (arrays).

JSON supports six data types: strings, numbers, booleans (true / false), null, objects, and arrays. These types can be nested arbitrarily, making JSON flexible enough to represent any structured data.

Today JSON is the dominant format for REST APIs, configuration files, NoSQL databases, and inter-service communication in microservice architectures. It has largely replaced XML in web services due to its simpler syntax and native compatibility with JavaScript.

JSON Validator

JSON Validator Online checks the integrity and syntax of JSON data based on the JavaScript Object Notation Data Interchange Format specification (RFC 8259).

🔍 Pinpoint Errors

When validation fails, the error message highlights the exact position of the problem — making it straightforward to locate and fix the issue without scanning through the entire document.

🌐 Browser-Only

Your JSON data is validated entirely in the browser. Nothing is sent to any server. To validate JSON you just need internet access — no software installation required.

⚡ Instant Results

Toggle "Auto-format on paste" and validation runs the moment you paste. For large payloads, click Validate Only to check without reformatting.

🔧 Works as JSON Lint

This tool doubles as a JSON Lint — identifying not just invalid JSON but also common mistakes like trailing commas, unquoted keys, and single-quoted strings.

🔒 Safe & Secure

All formatting and validation runs entirely in your browser using JavaScript's built-in JSON.parse and JSON.stringify. Your data never leaves your device — no server, no logging, no data retention.

✅ Completely Free

Our tool is free to use with no limits on input size or number of requests. No account required. From now on, you don't need to download any software for JSON formatting and validation tasks.