JSON Formatter & Validator
Format, validate, and beautify your JSON with syntax highlighting and tree view
Formatted JSON will appear here
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JSON Formatter, Validator & Beautifier — Free Online Tool
Paste raw or minified JSON and instantly format it with proper 2-space indentation, syntax highlighting, and error detection. Switch to tree view to navigate complex nested structures. Completely browser-based — your data stays private.
What This Tool Does
- Format / Beautify — Adds proper indentation (2 spaces) and line breaks to minified JSON
- Minify — Removes all whitespace, reducing file size for production use
- Validate — Checks JSON syntax and reports the exact error location (line number)
- Syntax Highlighting — Keys in indigo, strings in green, numbers in amber, booleans in purple
- Tree View — Interactive collapsible tree for navigating deeply nested JSON
- Structure Analysis — Shows total keys, values, max depth, and file size
Common JSON Syntax Rules to Remember
- All keys must be in double quotes:
"name": "Alice"✅ —name: "Alice"❌ - No trailing commas after the last element in an object or array
- No comments —
// commentis not valid JSON - Strings must use double quotes — single quotes are not allowed
- Boolean values must be
trueorfalse(lowercase), notTrue - Null values must be
null, notundefinedorNone
Use Cases
- API debugging — Paste API responses from Postman or browser DevTools
- Config files — Format package.json, tsconfig.json, .eslintrc files
- Data exploration — Use tree view to understand complex nested structures
- Production optimization — Minify JSON before embedding in HTML or scripts
Frequently Asked Questions
How do I format JSON?
Simply paste your JSON into the input area on the left. The tool automatically formats it with proper indentation and syntax highlighting. You can also click the 'Format/Beautify' button to ensure perfect 2-space indentation.
What is valid JSON?
Valid JSON must follow strict syntax rules: keys and strings must be in double quotes, no trailing commas, no comments, and values must be valid types (string, number, object, array, boolean, or null). Objects use curly braces {}, arrays use square brackets [].
What's the difference between JSON and JavaScript objects?
JSON is a text format for data exchange, while JavaScript objects are actual runtime data structures. Key differences: JSON requires double quotes around keys, doesn't allow trailing commas, doesn't support undefined or functions, and must be parsed before use in JavaScript.
Why is my JSON invalid?
Common JSON errors include: single quotes instead of double quotes, trailing commas at the end of arrays/objects, unquoted keys, comments (not allowed), undefined values, and unescaped special characters in strings. The validator will highlight the exact error and line number.
What does JSON minification do?
Minifying JSON removes all whitespace, newlines, and unnecessary characters while keeping the data identical. A minified JSON is smaller in file size and faster to transmit over a network. It's standard practice to minify JSON in production APIs and configuration bundles.
What is JSON tree view?
Tree view displays your JSON as a collapsible, hierarchical tree instead of raw text. Each object and array becomes an expandable node, making it easy to navigate deeply nested JSON structures. Click the ▼ arrow on any node to collapse or expand it.
What does 'depth' mean in JSON analysis?
Depth refers to how many levels of nesting your JSON has. A flat object like {"name": "Alice"} has depth 1. An object with nested objects inside adds depth. Deeply nested JSON (10+ levels) can cause performance issues in some parsers.
Can I validate JSON from an API response?
Yes. Copy the raw response body from your browser DevTools (Network tab → response), API client (Postman, Insomnia), or any terminal tool. Paste it into the input field and the validator will instantly check if it's valid JSON.
Does JSON allow comments?
No. Standard JSON (RFC 8259) does not support comments. This is a common source of errors when people copy JSON from documentation that includes comments for explanation. Use JSONC (JSON with Comments) format for config files that allow comments, like VS Code's settings.json.
How do I fix 'Unexpected token' JSON errors?
This typically means a syntax error near the reported position. Common causes: a missing comma between properties, an extra comma at the end of a list (trailing comma), an unquoted string key, or a single-quoted string. Look at the line number shown and fix the character at that position.