Free JSON Formatter & Validator Online

Beautify, minify, and validate JSON with live syntax highlighting, an error panel with line numbers, and a collapsible tree view. Everything runs in your browser.

100% free
No signup
Runs in your browser

Indent

Input

0 chars 0 keys

Output

Guide

What is JSON formatting?

JSON (JavaScript Object Notation) is the most common format for exchanging structured data between programs. Formatting (also called beautifying or pretty-printing) adds consistent indentation and line breaks so a dense, machine-generated JSON string becomes readable, with nested objects and arrays clearly stepped. This tool formats, minifies, and validates JSON with a collapsible tree view.

Format vs. minify

Formatting and minifying are opposites applied to the same data. Formatting expands JSON for humans to read and debug. Minifying removes all unnecessary whitespace to make the smallest possible payload for transmission, which is what you send over the network. Neither changes the data itself, only its presentation.

Validating JSON and common errors

Invalid JSON is a frequent source of bugs. The validator pinpoints the line where parsing fails. The usual culprits are: trailing commas after the last item, single quotes instead of double quotes, missing quotes around keys, unescaped characters inside strings, and comments (which standard JSON does not allow). Fixing the flagged line usually resolves the whole document.

Your data stays local

All parsing, formatting, and validation happen in your browser using the native JSON engine. Nothing you paste is sent to a server, so it is safe to format API responses, config files, or other data you would not want to upload. The tree view lets you collapse large structures to focus on the part you care about.

Last updated: July 2026

Frequently Asked Questions

What is JSON formatting?

JSON formatting (or beautifying) adds indentation and line breaks to compact JSON, making it human-readable. Minifying does the reverse - removing all whitespace to reduce file size.

How do I validate JSON?

Paste your JSON into the editor above. The tool will instantly tell you if your JSON is valid or show the exact line and character position of any errors.

What is the difference between JSON format and minify?

Formatting adds whitespace and indentation for readability. Minifying removes all unnecessary whitespace to produce the smallest possible JSON string for use in APIs or storage.

Is my JSON data sent to a server?

No. All formatting and validation happens entirely in your browser using JavaScript. Your data is never transmitted anywhere.

What causes invalid JSON?

Common causes include trailing commas, single quotes instead of double quotes, unquoted keys, missing colons, and unclosed brackets or braces.