JSON Formatter

The formatter is the home page. Paste JSON on the left; the formatted result appears on the right as you type.

Format and minify

• Beautify indents with 2 spaces, 4 spaces or tabs.
• Minify removes all whitespace — useful for configs and API payloads.
• Sort keys orders object keys alphabetically at every level, which makes documents easy to compare by eye.

Validation and errors

When the JSON is invalid you get the exact line and column and a plain-English message, for example:

Line 3, column 3: Expected ',' or '}' but found '"'

The faulty line is highlighted in the editor. Jump to the error moves your cursor there. While the input is invalid, the output keeps showing the last valid result (dimmed).

Common messages:

Message	Usual cause
Trailing comma is not allowed in JSON	[1, 2,] or {"a": 1,}
Keys must use double quotes	{'a': 1} or {a: 1}
Unescaped control character in string	A real line break inside "…" — use \n
Unexpected … after the end of the JSON value	Two documents pasted together, or extra text

Repair

Repair JSON fixes the most common problems in one click: trailing commas, single quotes, unquoted keys, comments, missing commas or brackets, Python-style True / False / None, and JSON wrapped in other text (like an AI chat reply or a log line).

For harder cases, ✦ AI Fix can repair JSON the rule-based repair can’t — see AI features. Always review AI-fixed output.

Tree view

Switch the output to Tree to explore large documents:

• The first two levels open automatically; deeper levels load when you expand them, so even very large files stay fast.
• Hover any row and click its path to copy a JSONPath, such as $.orders[0].customer.email.
• Expand all / Collapse buttons are at the top right.

Big numbers

Most online formatters run your JSON through JavaScript’s JSON.parse, which silently rounds integers above 9,007,199,254,740,991. CurlyJSON uses its own parser and keeps every number exactly as written — safe for 64-bit IDs, snowflake IDs and financial values. It also keeps your number formatting (1.50 stays 1.50).

Files and sharing

• Open file or drag a .json file onto the input (up to 50 MB).
• Copy and Download save the formatted output.
• Share copies a link containing your JSON (see Privacy).