Make messy JSON readable in one click. Paste your JSON below to validate it, see clear error messages, and get a neatly formatted or minified version.
Your JSON is processed in your browser only. It is never sent to any server or stored anywhere.
1. Paste your JSON into the box. 2. Click Format JSON for a readable version, or Minify JSON for a compact one-line version. 3. Copy the result, or read the error message if the JSON is invalid.
JSON (JavaScript Object Notation) is the most common way for websites and apps to exchange data. A typical API returns JSON like {"name":"Ali","age":30}, but real JSON from an API is often one long line with no spaces, which is almost impossible to read. This free JSON formatter fixes that: paste any JSON, and it shows a neatly indented, readable version with 2-space indentation. If the JSON has a mistake, it tells you exactly what is wrong instead of just failing silently.
JSON is used everywhere in modern software: web APIs, config files, mobile apps, and even this website's own data. Developers, students and testers all need to read JSON every day. A formatter saves time and prevents errors, because a missing comma or a wrong quote can break a whole program, and finding that mistake by eye in a long line is very hard.
Take this messy JSON: {"name":"Ali","age":30,"city":"Lahore","skills":["HTML","CSS"]}. It is valid, but hard to read. Paste it into the box above and click Format JSON, and you get a clean version with each key on its own line, the skills list spread over several lines, and clear indentation. Now click Minify JSON, and you get the same data back on one line with no extra spaces, which is how JSON is usually sent over the internet. Try both buttons and compare the results.
Now paste this broken JSON: {"name":"Ali","age":30,}. The problem is the trailing comma after 30 — JSON does not allow a comma after the last item. The formatter shows "Invalid JSON" and an error message about an unexpected token, which points you to the end of the line. Remove the comma and format again, and it works. Another common mistake is using single quotes: {'name':'Ali'} is not valid JSON, because JSON needs double quotes around keys and strings. Fix the quotes and the formatter will accept it.
JSON has a few strict rules. Keys must be in double quotes, not single quotes. Strings must use double quotes too. Numbers are written plainly, without quotes. Values can be strings, numbers, true, false, null, arrays (in square brackets) or objects (in curly braces). There must be no comma after the last item in an object or array, and there must be no comments. For example, this is valid: {"name":"Ali","age":30,"active":true,"tags":["a","b"],"address":null}. If any rule is broken, the JSON is invalid and a program will refuse to read it.
Format before you read. Always format API responses before trying to understand them; a one-line response hides the structure. Minify before you send. Minified JSON is smaller and faster to send over the internet. Read the error message. The error usually tells you where the problem is, such as an unexpected comma or quote. Check quotes first. Most JSON errors come from single quotes or a missing quote, so check those first. Copy the formatted result. Paste the clean version into your code or your notes, not the messy original.
Using single quotes. JSON needs double quotes for keys and strings; single quotes make it invalid. Leaving a trailing comma. A comma after the last item in an object or array is not allowed in JSON. Forgetting to close a bracket. Every { needs a } and every [ needs a ], and they must close in the right order. Adding comments. JSON does not support comments, so // notes will break it. Pasting JavaScript instead of JSON. JavaScript objects can have unquoted keys and functions, but JSON cannot, so they are not the same thing.
Pro Tip: If an API gives you a huge JSON response, format it first, then use your browser's find (Ctrl+F) to search for the key you need — it is much faster than reading the whole file.
Note: Your JSON never leaves your device. Formatting happens entirely in your browser, so it is safe to use even with private data.
What is JSON? JSON (JavaScript Object Notation) is a text format for storing and exchanging data. It looks like {"name":"Ali","age":30} and is used by almost every website API.
What does a JSON formatter do? It takes messy, one-line JSON and shows it with clear indentation and line breaks, so you can read and understand the structure easily.
Why is my JSON invalid? The most common reasons are a missing comma, a trailing comma after the last item, single quotes instead of double quotes, or an unclosed bracket. This tool shows the error message to help you find it.
What is the difference between Format and Minify? Format spreads the JSON over many lines with indentation so it is easy to read. Minify squeezes it onto one line with no extra spaces so it is smaller and faster to send.
Can I format JSON with single quotes? No. Valid JSON needs double quotes for keys and strings. Replace single quotes with double quotes and try again.
Is my JSON data safe in this tool? Yes. The formatting happens in your browser only. Your JSON is never sent to a server or stored anywhere.
What is the difference between JSON and JavaScript objects? They look similar, but JSON is stricter: keys must be in double quotes, there are no functions, no comments and no trailing commas. A JavaScript object is more flexible.
Can this tool handle large JSON files? Yes, for most normal sizes. Very large files (many megabytes) may be slow in the browser, so split them into smaller parts if the tool feels slow.