JSON Formatter

Format, beautify and validate JSON data with syntax highlighting.

Minified JSON from an API response is technically valid and practically unreadable. Paste it here to expand it with indentation and syntax colors, collapse it back to one line for production, or run the validator when something upstream refuses to parse and you need the exact error.

What This Tool Does

Beautify - Takes compressed JSON and adds indentation and line breaks so you can read it.
Minify - Removes extra whitespace to shrink the output.
Validate - Checks whether the text is strict JSON and returns the parser error if it fails.
Highlight - Colors keys, strings, numbers, booleans and null values in the formatted output.

Why JSON Breaks

Most JSON errors come from a few repeat mistakes. Trailing commas are common because JavaScript allows them in objects and arrays, but JSON does not. Single quotes are another one. JSON requires double quotes for keys and string values.

Other common problems include unquoted property names, comments, missing brackets and unescaped line breaks inside strings. If a config file works in one app but fails in another, it may be JSONC or JSON5 rather than strict JSON.

JSON vs. JavaScript Objects

They look similar, but they are not the same format. JavaScript objects can be more relaxed. JSON is stricter because it is meant for data exchange between different systems. If you copy a JavaScript object into a JSON API request, remove comments, trailing commas and single quotes first.

Working with Large JSON

The formatter is useful for API responses, webhook payloads and config snippets. For very large files, use a desktop editor or a command-line tool like jq. Browser tools are best for quick inspection, not for multi-megabyte production logs.

How to Use

Paste raw or minified JSON into the input box.
Click Format to beautify it.
Click Validate if you only want to check the syntax.
Copy the formatted or minified output.

Frequently Asked Questions

What makes JSON invalid?

The usual suspects are trailing commas, single quotes instead of double quotes, unquoted keys, comments and missing closing brackets. The validator returns the parser error so you have a clear place to start.

Can I minify JSON here too?

The Minify button strips all whitespace and line breaks in one go. Handy right before sending JSON in an API request or storing it somewhere space matters.

Why does my JavaScript object fail validation?

JavaScript objects and JSON look alike but have different rules. JS allows single quotes, trailing commas and unquoted keys. JSON requires double quotes on everything and no trailing commas. Copy your JS object here and the validator will show you what needs fixing.

Is there a size limit?

The tool handles files up to several megabytes without issues. For very large files (10MB+), a local tool like VS Code or the jq command-line utility will give you better performance.

Does JSON support comments?

Standard JSON does not support any type of comments. If you need comments, look into JSONC (JSON with Comments) or JSON5. Both are extensions that allow comments, but most APIs expect strict JSON.