JSON Formatter & Validator

Paste raw JSON to validate it instantly, then pretty-print it with your choice of indentation or collapse it to a minified single line.

What Is a JSON Formatter?

A JSON formatter (also called a JSON pretty-printer) takes compact or unindented JSON and adds whitespace, line breaks, and indentation to make it easy to read. A JSON validator checks whether your text conforms to the JSON specification — catching missing quotes, trailing commas, mismatched brackets, and other common mistakes.

When to Use This Tool

Debugging API responses — Paste a raw API response and instantly see the nested structure without squinting at a wall of text.

Minifying for production — Strip all whitespace to reduce payload size before embedding JSON in HTML, config files, or HTTP responses.

Validating config files — JSON is used for package.json, tsconfig.json, .eslintrc, and countless other config files. A quick validation pass catches syntax errors before they break your build.

JSON Syntax Rules

A valid JSON document must follow these rules:

• Strings must be in double quotes (single quotes are not valid)
• Object keys must be strings in double quotes
• Trailing commas after the last item in an array or object are not allowed
• true, false, and null are lowercase keywords, not strings
• Numbers cannot have leading zeros (e.g. 01 is invalid)

Frequently Asked Questions

Is my JSON data sent to a server? No. All processing happens in your browser using JavaScript. Nothing you paste is ever transmitted anywhere.

What is the difference between pretty-print and minify? Pretty-printing adds newlines and indentation so humans can read the structure. Minifying removes all non-essential whitespace to produce the smallest possible string — useful for reducing file size in production.

Can I format very large JSON files? Yes, up to the memory limits of your browser tab. Files in the tens of megabytes should work fine in modern browsers.