What Is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. It's easy for humans to read and write, and easy for machines to parse and generate. It's the dominant format for API responses, configuration files, and data exchange on the web.

JSON Syntax Rules

Data is in key/value pairs: "name": "value"
Data is separated by commas
Curly braces { } hold objects
Square brackets [ ] hold arrays
Keys must be strings in double quotes
Values can be: string, number, object, array, boolean, or null
No trailing commas allowed
No comments allowed

Example

{
  "name": "MultiTooSite",
  "version": "1.0",
  "tools": ["json", "base64", "url"],
  "active": true,
  "count": 55,
  "author": {
    "name": "Nasir Badar",
    "website": "https://multitoosite.com"
  },
  "tags": null
}

How to Use This Tool

Paste or type JSON into the input box — it auto-formats as you type (if enabled).
Click Format / Beautify to pretty-print with indentation.
Click Minify to strip all whitespace for the smallest possible output.
Click Validate to check for syntax errors without changing the output.
Click Sort Keys to alphabetize object keys (useful for diffing).
Switch between Code, Raw, and Tree views in the output header.

Output Views

Code view: Syntax-highlighted, color-coded, pretty-printed JSON. Best for visual inspection.
Raw view: Plain text in an editable textarea. Best for copying out to paste elsewhere.
Tree view: Interactive collapsible tree. Best for exploring large or deeply nested JSON.

Options Explained

Indent spaces: How many spaces to use for each level. Use 2 for compact, 4 for readability, or 0 for no indentation (like minify).
Sort keys alphabetically: Sorts keys at every level A → Z. Great for comparing two JSON files side by side.
Escape Unicode characters: Replaces non-ASCII characters with their \uXXXX escape sequences. Useful for safe transport over ASCII-only channels.
Auto-process on input: Format JSON automatically as you type. Disable this if you want to manually trigger formatting.

Common Errors You Might See

Unexpected token — usually a missing or extra comma, or an unquoted key.
Unexpected end of input — usually a missing closing brace } or bracket ].
Trailing comma — JSON doesn't allow trailing commas: [1, 2, 3,] is invalid.
Single quotes — JSON requires double quotes for strings and keys.
Unquoted keys — {name: "x"} is invalid; must be {"name": "x"}.
Comments — JSON doesn't allow // or /* */ comments. Use JSONC or YAML if you need comments.

Common Use Cases

Debugging API responses — paste a raw response to see its structure.
Cleaning config files — reformat package.json, tsconfig.json, or similar files.
Diffing JSON — sort keys then compare two versions.
Minifying for production — strip whitespace before serving JSON.
Validating before commit — catch syntax errors before they break builds.
Exploring large payloads — use the tree view to navigate complex structures.

Related Tools

Base64 Encoder / Decoder — encode binary data to Base64.
URL Encoder / Decoder — encode URLs and query strings.
HTML / CSS Beautifier — format code for readability.
Regex Tester — test regular expressions live.

Privacy Note

All JSON formatting, validating, and syntax highlighting happens in your browser. Your data is never uploaded to a server, never stored, and never shared.

JSON Formatter & Validator