Features of This JSON Formatter
This tool formats and minifies JSON data in real-time. Just paste JSON into the text area and the formatted result appears instantly — no button clicks needed. Syntax highlighting color-codes keys, strings, numbers, and booleans for quick visual parsing. Syntax errors are detected with line and column numbers, and the error line is highlighted. The standout feature is 'Fix JSON' — auto-repair for trailing commas, single quotes, comments, and other non-standard syntax. It instantly fixes 'almost valid' JSON that causes parse errors during API development and debugging. All processing happens in your browser. Your data is never sent to any server. Dark mode is also supported.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight text format for data interchange. Originally derived from JavaScript object syntax, it's now standardized as a language-independent format (ECMA-404). JSON is used for Web API requests/responses, configuration files, NoSQL database documents, and more. Compared to XML, it's more compact and has natural affinity with JavaScript.
How to Use
Paste JSON data into the left panel (or drag & drop a file) and the formatted result appears in real-time on the right. Choose from 2 spaces (default), 4 spaces, or tab indentation. 'Minify' mode removes all whitespace. Enable 'Sort Keys' to alphabetically sort object keys. Copy the result or download it as a .json file.
JSON Syntax Rules
JSON syntax is strict. Keys must be double-quoted (single quotes and unquoted keys are invalid). String values must also be double-quoted. Numbers, true/false, and null are written without quotes. Arrays use square brackets, objects use curly braces. Elements are separated by commas, but trailing commas (after the last element) are not allowed. Comments are also not permitted in standard JSON. The 'Fix JSON' feature can auto-repair these violations.
VS Code vs This Tool
VS Code has built-in JSON formatting (Shift+Alt+F / Shift+Option+F). For developers who use VS Code daily, that's convenient. However, this tool requires no installation and works in any browser — ideal for tablets, shared computers, or checking CI logs. The 'Fix JSON' auto-repair feature is not available in VS Code's standard formatter.
What is JSON Minification?
JSON minification removes all indentation, line breaks, and extra whitespace, compressing JSON into a single line. The data meaning is preserved, but file size is significantly reduced. It's useful for reducing API payload size, saving storage, and compacting log files. Click 'Minify' to instantly see the compressed result.
Frequently Asked Questions
- What is JSON formatting?
- JSON formatting adds indentation and line breaks to make JSON data human-readable. This tool formats in real-time, detects syntax errors with line numbers, and can auto-repair broken JSON.
- What tools can make JSON readable?
- This tool is a free online JSON formatter that works entirely in your browser. Just paste your JSON and it's instantly formatted with syntax highlighting. No installation required.
- What are the JSON formatting rules?
- JSON (JavaScript Object Notation) follows strict rules: keys must be double-quoted, string values must be double-quoted, numbers/booleans/null are unquoted, arrays use square brackets, objects use curly braces, and trailing commas are not allowed.
- Is my data sent to a server?
- No. All processing happens entirely in your browser. Your data is never sent to any server. You can safely format JSON containing API keys or credentials.
- Can you fix broken JSON?
- Yes. The 'Fix JSON' button auto-repairs trailing commas, single quotes, comments (// and /* */), and other non-standard JSON syntax. It's useful for converting JavaScript objects to valid JSON.