JSON Formatter & Validator
JSON Formatter & Validator is a free online tool that formats, validates, and explores JSON with syntax highlighting, tree view, code folding, Find & Replace, JSONPath table, and real-time statistics. No signup, works entirely in your browser.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, human-readable data format used for exchanging information between systems. It has become the de facto standard for APIs, configuration files, and data storage across virtually all programming languages and platforms. The format is defined in the JSON specification (ECMA-404 / RFC 8259).
A JSON document can contain objects (key-value pairs wrapped in curly braces), arrays (ordered lists in square brackets), strings, numbers, booleans (true/false), and null. These can be nested to any depth, making JSON flexible enough to represent complex data structures.
Despite its simplicity, working with raw JSON — especially deeply nested API responses or large config files — can be challenging without proper tooling. That's where an online JSON formatter, validator, and viewer comes in. Whether you need to pretty print a minified API response, validate JSON syntax before deployment, or simply explore a complex data structure, a dedicated JSON editor saves time and prevents errors.
What is a JSON Formatter?
A JSON formatter (also known as a JSON beautifier or JSON pretty printer) is a tool that takes raw or minified JSON data and reformats it with proper indentation, line breaks, and syntax highlighting to make it human-readable. A JSON validator checks whether your JSON conforms to the specification and reports syntax errors with their exact line and column location.
This tool combines both functions: it acts as a JSON formatter, JSON validator, JSON viewer, JSON editor, and JSON linter — all in one interface. Unlike many online JSON tools, it runs 100% in your browser. Your data is never sent to any server, making it safe for sensitive API responses, configuration files, and production data.
Developers, QA engineers, DevOps teams, and data analysts use JSON formatters daily to debug API responses, validate configuration files, inspect webhook payloads, and prepare test data. If you work with REST APIs, GraphQL, or any modern web service, a JSON formatter is an essential part of your toolkit.
How to Format JSON Online
This free online JSON beautifier lets you format, validate, and explore JSON directly in your browser — no installation, no signup, no data sent to any server.
- Paste your JSON — Click the Paste button or press Ctrl+V (Cmd+V on Mac) to paste JSON from your clipboard. The tool auto-formats valid JSON.
- Format or minify — Click Format to pretty print JSON with proper indentation. Click Minify to remove all whitespace and compress the output.
- Explore the structure — Switch to the Tree tab for an interactive JSON viewer. Click any key to copy its JSONPath. Click a leaf value to jump to its line in the editor.
- Search and replace — Press Ctrl+F (Cmd+F) to find text, Ctrl+H (Cmd+H) to find and replace. Navigate matches with Enter/Shift+Enter.
- Inspect paths — The Paths tab shows every leaf value with its full JSONPath, type, and value. Sort, filter, and click to navigate.
- Check statistics — The analytics panel shows document size, nesting depth, type distribution, and deep insights like the heaviest key and longest string.
- Copy the result — Use Copy for the formatted version or Copy Mini for the minified version.
How to Validate JSON
JSON validation checks that your data follows the correct syntax rules. This JSON checker validates your input in real time as you type, showing errors with exact line and column numbers. Common reasons validation fails include trailing commas, single quotes instead of double quotes, unquoted keys, and missing separators.
To validate JSON: paste or type your data in the editor. The validation bar at the bottom instantly shows a green checkmark for valid JSON or a red indicator with the error location and message. You can also use the Smart Search bar to navigate directly to any key using JSONPath notation (for example, $.settings.theme).
JSON Syntax Reference
Objects
Key-value pairs in curly braces. Keys must be double-quoted strings. Values can be any JSON type. {"key": "value", "count": 42}
Arrays
Ordered lists in square brackets. Can contain any JSON value, including mixed types. [1, "two", true, null]
Strings
Double-quoted text with escape sequences: \n (newline), \t (tab), \" (quote), \\ (backslash), \uXXXX (Unicode).
Numbers, Booleans & Null
Numbers can be integers or floats with optional exponent: 42, 3.14, 1e10. Booleans are true/false. null represents an empty value.
Common JSON Errors
When your JSON fails to parse, the validator highlights the exact error location. Here are the most frequent mistakes:
| Error | Example | Fix |
|---|---|---|
| Trailing comma | {"a": 1,} | Remove the comma after the last item |
| Single quotes | {'key': 'val'} | Use double quotes for keys and strings |
| Unquoted keys | {key: "val"} | Wrap keys in double quotes |
| Comments | // not allowed | Remove comments; use JSONC or JSON5 if needed |
| Missing separator | {"a" "b"} | Add colon between key and value, comma between pairs |
Frequently Asked Questions
What does this tool do? ▾
It formats, validates, and explores JSON with syntax highlighting, tree view, code folding, Find & Replace, JSONPath table, and real-time statistics — all directly in your browser with zero data sent to any server.
Is my data safe? ▾
Yes. Everything runs 100% client-side in your browser. Your JSON is never uploaded, logged, or sent anywhere. We don't use cookies or tracking.
Can I search within my JSON? ▾
Yes. Press Ctrl+F (Cmd+F on Mac) for Find, and Ctrl+H (Cmd+H) for Find & Replace. It supports incremental search with a match counter, navigation between matches, and case sensitivity toggle.
What is JSONPath? ▾
JSONPath is a notation for navigating to specific values in a JSON document, like $.store.book[0].title. The Paths tab shows every leaf value with its full JSONPath, making it easy to reference specific data points.
Can I fold/collapse sections? ▾
Yes. Click the triangle icons in the editor gutter to collapse or expand objects and arrays. Use the Collapse All and Expand All buttons in the toolbar for bulk operations.
Does it work offline? ▾
Yes. After the initial page load, the tool works entirely offline since all processing happens in your browser. Your content is also auto-saved to localStorage.
What JSON features are supported? ▾
Pretty-print with configurable indent (2/4 spaces or tabs), minify, syntax highlighting, code folding, interactive tree view, JSONPath table, Find & Replace, and comprehensive statistics including key count, depth, and type counts.
Is it free? ▾
Yes, it is completely free forever. No signup required, no ads, no usage limits.