JSON Formatter & Beautifier
Format, minify, sort keys, and validate JSON — all in your browser, nothing sent to any server
Formatted JSON will appear here.
What Is a JSON Formatter?
A JSON formatter — also called a JSON beautifier, JSON pretty printer, or JSON indenter — takes raw, compact, or inconsistently indented JSON text and reformats it with clean, readable indentation and line breaks. Whether you received minified JSON from an API, copied a response from browser DevTools, or generated JSON programmatically without formatting, a JSON formatter transforms it into a human-readable structure in one click.
This tool supports three indentation styles:
- 2 spaces — the most common choice, used by many style guides including the Google JSON Style Guide and Prettier defaults
- 4 spaces — preferred in Python and some backend languages
- Tab — useful when tab indentation is required by your project or editor settings
JSON Beautifier vs JSON Minifier
These are two opposite operations:
JSON beautifier (this tool’s Format button) expands compact JSON by adding newlines and indentation. It makes JSON easy to read, inspect, and debug, but increases file size. Use it during development, debugging, and code review.
JSON minifier (this tool’s Minify button) strips all unnecessary whitespace — spaces, tabs, and newlines — from a JSON document to produce the smallest valid JSON string. This reduces payload size for API responses, configuration files, and data stored in databases. Use it before committing production configurations or shipping data over the network.
Example — the same JSON before and after formatting:
{"name":"Alice","age":30,"hobbies":["reading","coding"]}After formatting with 2-space indentation:
{
"name": "Alice",
"age": 30,
"hobbies": [
"reading",
"coding"
]
}JSON Validator
The built-in JSON validator checks your JSON for syntax errors using the browser’s native JSON.parse function. When a problem is detected, the tool reports the exact line number and column where parsing failed — so you can jump directly to the problematic character without scanning the entire document.
Common JSON syntax errors include:
| Error | Example | Fix |
|---|---|---|
| Missing comma | {"a":1 "b":2} | Add , after 1 |
| Trailing comma | {"a":1,} | Remove the last , |
| Unquoted key | {name:"Alice"} | Quote the key: {"name":"Alice"} |
| Single quotes | {'name':'Alice'} | Use double quotes: {"name":"Alice"} |
| Mismatched bracket | {"a":[1,2} | Change } to ] |
| Undefined / comments | {"a": undefined} | JSON does not support undefined or comments |
Sort Keys Alphabetically
The Sort Keys feature recursively sorts all object keys in alphabetical order at every nesting level. Array element order is preserved — only object keys are sorted.
Sorting keys is useful for:
- Diffing — comparing two versions of a JSON document is much easier when keys appear in the same predictable order
- Version control — sorted keys eliminate spurious diffs caused by key reordering
- API response comparison — comparing responses from different endpoints or different API versions
- Readability — predictable key order makes large JSON objects easier to navigate
How JSON Formatting Works
JSON (JavaScript Object Notation) is defined in RFC 8259 and ECMA-404. It represents data as key-value pairs (objects), ordered lists (arrays), strings, numbers, booleans (true / false), and null.
Formatting does not change the data — it only changes whitespace. A formatted JSON document and its minified counterpart represent exactly the same data structure and parse to the same value in every language.
Common Use Cases
API development: Copy a JSON response from browser DevTools or a REST client like Postman or curl, paste it into the formatter, and instantly see the structure with syntax highlighting.
Configuration files: Format package.json, tsconfig.json, appsettings.json, or any other JSON configuration file before committing to version control.
Log inspection: Server logs often contain minified JSON event payloads. Paste them here to read them at a glance.
Data validation: Before sending JSON to an API or storing it in a database, validate it here to catch syntax errors early.
Comparing responses: Use Sort Keys then copy both JSON documents into a diff tool for a clean comparison free of key-ordering noise.
Frequently Asked Questions
What is the difference between JSON and JavaScript objects?
JSON is a strict text format derived from JavaScript object literal syntax, but it has important restrictions: all keys must be double-quoted strings, values must be one of the six JSON types (string, number, boolean, null, object, array), and features like comments, trailing commas, undefined, NaN, Infinity, and functions are not allowed.
Why does JSON use double quotes and not single quotes? The JSON specification (RFC 8259, Section 7) mandates double-quoted strings. Single-quoted strings are valid in JavaScript object literals but not in JSON. Many JSON parsers will reject single-quoted strings.
What is the maximum JSON size this tool can handle? The formatter operates entirely in your browser using JavaScript. It can handle JSON files well over 1 MB without noticeable delay on modern hardware. For very large files (10+ MB), use the Minify output option and avoid syntax highlighting to keep rendering fast.
Can I format JSON with comments (JSON5 or JSONC)?
Standard JSON does not support comments. This tool validates against the strict JSON specification. If your file contains // comments or /* block comments */ (as in JSONC or JSON5), remove them first or use a dedicated JSON5 parser.
Is my JSON data private? Yes. All formatting, minification, sorting, and validation runs entirely in your browser. No data is sent to any server. Your JSON never leaves your device.