Free JSON Formatter & Validator Online

Paste messy JSON, press Format and get clean, readable output in a second. The tool also checks your syntax, shows the exact line and column of any error, and can minify or sort your data. Everything runs in your browser, so your data stays on your device.

How to use the JSON formatter

1. Paste your JSON into the Input box, or press Load sample to try an example.
2. Choose an indent size (2 spaces, 4 spaces or tab). Turn on Sort keys if you want every object ordered alphabetically.
3. Press Format to beautify, Minify to compress, or Validate to only check the syntax.
4. Press Copy result and paste the clean JSON into your code, API client or config file.

What this tool does

JSON (JavaScript Object Notation) is the most common format for sending data between a server and a web or mobile app. API responses often arrive as a single long line that is almost impossible to read. This formatter adds indentation and line breaks so you can see how objects and arrays are nested, and it tells you immediately if the data is not valid JSON.

Feature	What it gives you
Format / beautify	Readable output with your choice of 2 spaces, 4 spaces or tabs
Minify	Smallest possible JSON, ideal for API requests and storage
Validate	Pass or fail result with line and column of the first error
Sort keys	Alphabetical keys at every level, useful for comparing two files
Browser only	No upload, no account, no limit on usage

Common JSON errors and how to fix them

Most invalid JSON fails for a handful of reasons. If the validator reports an error, check these first.

Trailing comma

JSON does not allow a comma after the last item. {"a": 1, "b": 2,} is invalid. Remove the final comma.

Single quotes

Keys and string values must use double quotes. {'name': 'Ravi'} is valid JavaScript but invalid JSON. Use {"name": "Ravi"}.

Unquoted keys

Every key must be a quoted string. {name: "Ravi"} will fail.

Missing or extra brackets

Each { needs a matching } and each [ needs a matching ]. The error position usually points to where the structure stopped making sense.

Comments

Standard JSON does not support // or /* */ comments. Remove them before validating.

Invalid values

Use lowercase true, false and null. Values such as undefined, NaN and True are not valid.

When to use a JSON formatter

• Debugging API responses: make a raw response readable so you can find the field you need.
• Editing config files: check package.json, tsconfig.json or app settings before you commit them.
• Comparing data: sort keys in two files, then compare them in a diff tool.
• Reducing payload size: minify JSON before sending it in a request or saving it.
• Learning: beginners can see how objects, arrays, strings, numbers and booleans fit together.

Privacy and security

This tool processes your text locally using your browser's built-in JSON parser. Nothing you paste is sent to a server or stored. You can still avoid pasting passwords, API keys or personal data into any online tool as a good habit.

Frequently asked questions