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.

Need to convert JSON to another format? Use the JSON to YAML converter to convert JSON to YAML (or back) bidirectionally — useful when working with Kubernetes, Docker Compose, or other YAML-based config systems.

Starting with YAML instead of JSON? Use the YAML to JSON Converter when your config or manifest is YAML and you need valid JSON output quickly.

Working with a JWT token? JWT payloads are JSON objects encoded in base64url. Use the JWT Decoder to decode any JWT token and see its header and payload claims in a formatted, readable view — no keys required.

Need to clean query text too? If your workflow includes SQL snippets alongside JSON payloads, use the SQL Formatter to make long queries easier to review.