JSON Formatter
A fast, production-quality JSON formatter that beautifies, minifies, and validates JSON with a live tree view, syntax highlighting, and precise error location — all running locally in your browser.
Everything runs locally in your browser. Your JSON never leaves your device.
Beautify, minify, and validate JSON with a live tree view, syntax highlighting, error line/column reporting, and file upload — 100% local.
About the JSON Formatter
JSON is the default data format of the modern web, but pasting a compressed API response into a chat, log, or bug report makes it unreadable. This tool gives you a fast, private way to beautify, minify, validate, and explore JSON without leaving your browser. Parsing uses the browser's native JSON engine, and every action — from indent changes to tree expansion — happens locally. Nothing about your data is transmitted, logged, or stored.
Common use cases
- Making a minified API response readable for debugging or documentation. - Compressing a hand-edited config file before committing it. - Validating JSON copied from a log line or error message. - Exploring a deeply nested response with the tree view. - Fixing invalid JSON with precise line/column error messages. - Preparing JSON payloads for Postman, curl, or CI variables.
Tips for working with JSON
- Use 2-space indent for API payloads and 4-space for config files that humans will edit often. - Always minify before sending JSON in URLs or headers. - If the validator reports "Unexpected token", check for single quotes, trailing commas, or unquoted keys. - Use the tree view to inspect the shape of an unfamiliar API response before writing code against it. - Copy the minified output when embedding JSON in code — it avoids escaping issues.
Limitations
- Only strict RFC 8259 JSON is supported — comments (JSONC) and trailing commas (JSON5) are rejected. - File uploads are capped at 10 MB. For larger files, split them client-side. - Very deep or very wide structures may render slowly in the tree view; use the formatted view for those. - The tool does not diff two JSON documents — that is a separate tool.
Key features
Turn compressed JSON into cleanly indented, human-readable output with configurable indent size (0–8 spaces).
Strip whitespace to produce the smallest possible payload — perfect for API bodies and config files.
JSON is parsed as you type. Get instant feedback with a green tick for valid input or a precise error for invalid input.
Syntax errors report the exact line and column so you can fix problems in seconds, not minutes.
Explore deeply nested structures with an interactive tree. Expand and collapse any object or array.
Keys, strings, numbers, booleans, and null are color-coded for readability — with full dark mode support.
The input pane shows line numbers so error messages and code reviews line up.
Load JSON from a file (up to 10 MB) or download the formatted result with one click.
Copy the formatted or minified output to your clipboard instantly.
All parsing happens in your browser. Your JSON is never sent to a server, logged, or stored.