JSON Formatter & Validator – Free Online Tool

How to Format JSON

1. Paste your JSON data in the input area
2. Select your preferred indentation (2 spaces, 4 spaces, or tab)
3. Click "Format / Beautify" to prettify or "Minify" to compress
4. Copy the result or download as a file

Features

• Format/Beautify: Pretty-print JSON with proper indentation
• Minify: Remove whitespace for smaller file size
• Validate: Check for syntax errors with detailed messages
• Error Location: Shows exact position of errors
• Download: Save formatted JSON as a file

Why Use Our JSON Formatter?

• Instant: Real-time validation as you type
• Free: No limits, no signup required
• Private: All processing in your browser
• Developer Friendly: Keyboard shortcuts supported

What Is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format that has become the standard for web APIs, configuration files, and data storage. It was derived from JavaScript but is language-independent—virtually every modern programming language can parse and produce JSON.

A valid JSON document must start with either an object ({}) or an array ([]). Keys must be double-quoted strings, and values can be strings, numbers, booleans (true/false), null, arrays, or nested objects. Unlike JavaScript, JSON does not allow trailing commas, single-quoted strings, or comments.

When to Format vs. Minify

Format (Beautify) when you need to read, debug, or review JSON—for example, when inspecting API responses, editing configuration files, or sharing data with teammates. Indented JSON is dramatically easier to scan for errors.

Minify when you need to reduce payload size for network transmission or storage. Removing whitespace can reduce JSON size by 10–30 %, which matters for large datasets or bandwidth-constrained environments like mobile APIs.

Common JSON Errors and How to Fix Them

• Missing comma: Add a comma between key-value pairs and array elements.
• Trailing comma: Remove the comma after the last item in an object or array.
• Single quotes: Replace single quotes with double quotes around keys and string values.
• Unescaped characters: Escape special characters like backslashes (\\) and double quotes (\").
• Unmatched brackets: Ensure every { has a matching } and every [ has a matching ].

Limitations

This tool handles standard JSON as defined by json.org. It does not support JSON5 extensions (comments, trailing commas, unquoted keys). Very large files (over 10 MB) may be slow to format depending on your device’s memory and processor.