JSON Formatter

What JSON actually is

JSON (JavaScript Object Notation) is a lightweight text format for representing structured data objects made of key-value pairs, arrays, strings, numbers, booleans, and null. It's the format almost every web API returns data in, and it's used for configuration files, app settings, and data exchange between systems that don't share a programming language. Because it's just text, JSON can be hand-written, but small syntax mistakes are common and often hard to spot by eye in a dense, unformatted blob.

What does this JSON formatter do?

Paste any JSON data and click "Format / Beautify" to get a clean, indented, human-readable version useful for reading API responses, config files, or debugging data structures. Click "Minify" to strip all whitespace for a compact version, useful when file size matters.

Syntax errors this tool catches

Clicking "Format / Beautify" runs your text through a real JSON parser, so any syntax error is reported immediately with a specific error message rather than silently producing broken output. The most common mistakes it catches: a trailing comma after the last item in an object or array (valid in JavaScript object literals, but not valid JSON), missing or single quotes around a key or string value (JSON requires double quotes), an unescaped quote inside a string, and mismatched or missing brackets and braces.

Pretty-print vs. minify

Formatting ("Beautify") adds indentation and line breaks so nested objects and arrays are easy to read and scan visually useful when you're debugging an API response or reviewing a config file. Minifying strips all unnecessary whitespace, producing the smallest possible version of the same data useful when the JSON will be embedded in a URL, sent over a network where every byte counts, or stored where file size matters. Both operations use exactly the same underlying data; only the formatting changes.

A safe place for sensitive JSON

Because parsing and formatting both happen locally in your browser using JavaScript's built-in JSON parser, nothing you paste here is ever transmitted anywhere this tool works even without an internet connection once the page has loaded, which makes it reasonable to use for JSON containing internal config values or other data you wouldn't want to paste into a random online form.

FAQ

Is my data sent to a server?
No all parsing and formatting happens locally in your browser using JavaScript. Your JSON never leaves your device, making this safe for sensitive or private data.

Is there a size limit?
No hard limit is enforced, but extremely large JSON files (many megabytes) may be slow to process depending on your device.

What's a trailing comma error, and why does it matter?
A trailing comma is an extra comma after the last item in an object or array, like {"a": 1,}. It's allowed in JavaScript code but not in strict JSON, so a JSON parser will reject it this is one of the most common copy-paste errors when JSON is edited by hand.

Why does my JSON need double quotes instead of single quotes?
The JSON specification requires double quotes around keys and string values. Single quotes are valid in JavaScript object literals but not in JSON itself, so pasting JavaScript-style code here will often fail to parse until the quotes are fixed.

What's the difference between formatting and validating?
Formatting and validating happen together here if your JSON is invalid, formatting will fail and show you the specific parse error instead of a result, so a successful format also confirms the JSON is valid.

Can I format deeply nested JSON?
Yes there's no depth limit enforced by this tool; very deeply nested structures will just produce a taller, more indented result.