JSON Formatter & Validator
Instantly format, validate, and minify JSON in your browser. Syntax highlighting, error detection, key count, nesting depth — all client-side, nothing sent to a server.
Formatted output will appear here...
How to Use the JSON Formatter
Paste or type your raw JSON into the left input panel, then click one of the action buttons — Format, Minify, or Validate — to see the result in the right output panel immediately.
The Three Core Actions
Format (Pretty Print)
Parses your JSON and re-serializes it with 2-space indentation and newlines. Ideal for reviewing API responses, debugging, and sharing readable data.
Minify
Strips all whitespace to produce the most compact representation. Use this for production payloads, localStorage data, and bandwidth-sensitive APIs.
Validate
Checks syntax without changing the output. Returns a green badge for valid JSON or a red badge with the exact parser error message and position.
Understanding the Syntax Highlighting
The formatted output uses color-coded tokens to distinguish JSON data types at a glance:
| Token Type | Color | Example |
|---|---|---|
| Object keys | Electric green | "name": |
| String values | Amber | "hello world" |
| Numbers | Blue | 42, 3.14 |
| Booleans | Violet | true, false |
| Null | Muted gray | null |
Reading the JSON Statistics
After formatting or validating, a stats bar appears below the panels showing:
- Keys — the total number of object keys across all nesting levels. Useful for understanding data complexity.
- Nesting depth — how many levels deep the deepest value is. High depth (5+) can indicate over-complex data structures.
- Size — the byte size of the output string. Compare formatted vs. minified sizes to see the whitespace overhead.
Common JSON Errors and How to Fix Them
| Error | Cause & Fix |
|---|---|
| Unexpected token | A stray comma, missing quote, or unsupported value like undefined. Check the position shown in the error. |
| Trailing comma | JSON does not allow trailing commas after the last key-value pair or array item. Remove the comma. |
| Single quotes | JSON requires double quotes for all strings and keys. Replace every ' with ". |
| Unquoted keys | Unlike JavaScript object literals, JSON keys must be double-quoted: { name: 1 } → { "name": 1 }. |
| Comments | JSON does not support // or /* */ comments. Remove them before pasting. |
Privacy and Security
This tool runs entirely in your browser. No JSON data is transmitted to any server, logged, or stored. You can safely paste API keys, configuration files, database exports, and other sensitive data without any privacy concerns.
Frequently Asked Questions
What is a JSON formatter?
A JSON formatter (also called a JSON pretty printer) takes raw, compact JSON text and adds indentation and line breaks to make it human-readable. It helps developers quickly scan data structures, debug API responses, and share readable data with teammates.
How do I validate JSON?
Paste your JSON into the input panel and click the Validate button. The tool will parse your text using the browser's built-in JSON.parse() and display a green 'Valid JSON' badge if the syntax is correct, or a red 'Invalid JSON' badge with the exact error message and position if it is not.
What is the difference between Format and Minify?
Format (pretty-print) adds indentation and newlines so the JSON is easy to read — ideal when reviewing data or debugging. Minify removes all unnecessary whitespace, producing the smallest possible JSON string — ideal for API responses and production payloads to reduce bandwidth and load time.
Is my JSON data sent to any server?
No. All processing happens entirely in your browser using JavaScript's built-in JSON.parse() and JSON.stringify() functions. Your data never leaves your device, making this tool safe to use with sensitive configuration files, API keys, or private data.
What do the color-coded tokens mean in the output?
The syntax highlighting uses distinct colors for each JSON data type: green for object keys, amber for string values, blue for numbers, violet for boolean values (true/false), and muted gray for null. This makes it easy to scan deeply nested structures at a glance.
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