How to Format and Validate JSON Online

What is JSON Formatting?

JSON (JavaScript Object Notation) is the most common format for sending data between apps and APIs. But raw JSON often arrives as one long, unreadable line. Formatting (also called beautifying or pretty-printing) adds indentation and line breaks so you can actually read the structure — and validating checks that the syntax is correct.

Why Format JSON?

Debugging — spot a missing comma or bracket instantly
Readability — understand nested data at a glance
Sharing — paste clean, indented JSON into docs or tickets
Validation — confirm an API response is well-formed before using it

How to Format JSON (Step by Step)

Step 1: Open the JSON Formatter Go to the Kinsutools JSON Formatter.

Step 2: Paste your JSON Paste the raw JSON into the input box.

Step 3: Format Click "Format". The tool indents the JSON and instantly flags any syntax errors with a clear message.

Step 4: Copy the result Copy the clean, formatted JSON for use in your code, docs, or ticket.

Common JSON Errors the Validator Catches

Error	Cause
Trailing comma	A comma after the last item in an object or array
Missing quotes	Keys and string values must use double quotes
Single quotes	JSON requires double quotes, not single
Unclosed bracket	A missing closing brace or bracket

Tip: JSON is Not JavaScript

JSON looks like JavaScript objects, but it's stricter: keys must be in double quotes, no comments are allowed, and no trailing commas. When in doubt, run it through the validator.