Make JSON Readable in One Click
JSON is everywhere: API responses, configuration files, app settings, exported data and the structured data that helps your pages show up nicely in Google. Machines are happy to read it as one long line, but people aren't. A missing comma or an extra bracket hidden in a wall of text can waste an afternoon.
Paste your JSON into the box above and it is checked and neatly formatted straight away, with consistent indentation and one value per line. If something is wrong, you get a plain-English explanation and the exact line and column where the problem starts. Everything happens inside your browser, so private data such as API keys, customer records or tokens never leaves your device.
How to Use the JSON Formatter
- Paste your JSON into Input JSON, open a .json file, or drag one onto the box.
- Choose Format for readable output, Minify for the smallest possible version, or Tree to explore the data.
- Pick your indentation under Options: two spaces, four spaces or tabs.
- Click Copy or Save to download the result as a .json file.
Try the Demo button to load a sample that contains a few deliberate mistakes, then watch how the formatter explains and fixes them.
Clear Error Messages You Can Act On
Most validators simply say the JSON is invalid, or show a cryptic message with a character number. This tool tells you what is wrong in everyday words, such as "Trailing comma before }" or "Expected a property name in double quotes", along with the line and column. It also shows the problem line with a marker under the exact spot, and the Show in editor button jumps your cursor straight there.
These are the mistakes it sees most often:
- Trailing commas after the last item in an object or array, which JavaScript allows but JSON doesn't.
- Single quotes around keys or text. JSON only accepts double quotes.
- Unquoted keys, such as
{name: "Raj"}instead of{"name": "Raj"}. - Comments, which are common in config files but not part of the JSON standard.
- Missing commas between two values, usually after copying and pasting lines around.
- Python-style values such as True, False and None instead of true, false and null.
Fix Common Mistakes Automatically
When the formatter spots one of the mistakes above, a Fix it for me button appears. One click repairs the JSON and replaces your input with clean, valid code, and the Details panel lists exactly what was changed. If you work with relaxed formats like JSON5 or JavaScript objects all day, switch on Auto-fix common mistakes and every paste is repaired as you go. An Undo button is always there if you change your mind.
Explore Data with the Tree View
Large API responses can run to thousands of lines. Switch to Tree and the data becomes a collapsible outline. Each object and array shows how many keys or items it contains, so you can see the shape of the data before you dive in. Strings, numbers, true or false values and null each have their own colour.
Click on any key to copy its path, such as $.tools[1].name. That is handy when you are writing code that reads a value deep inside a response, or when you need to tell a colleague exactly where to look. To keep things quick, branches are only built when you open them, so even very large files stay responsive.
Big Numbers Stay Exact
Here is a trap many online formatters fall into. JavaScript can only store whole numbers exactly up to about nine quadrillion. A formatter that relies on the browser's built-in parser will silently round anything larger, so an order ID like 98765432109876543210 can come back as 98765432109876540000. That is a nasty bug to discover in production.
This formatter uses its own parser that keeps every number exactly as you wrote it, digit for digit, including long decimals. It also preserves the order of your keys unless you ask it to sort them, and it warns you about duplicate keys, which most tools quietly drop.
Format, Minify or Sort
Formatted JSON is perfect for reading, reviewing and committing to a code repository, because changes show up clearly line by line. Minified JSON removes every unnecessary space and line break, which makes API payloads and stored data smaller. The Details panel shows how much smaller it gets.
Turning on Sort keys A–Z puts every object's keys in alphabetical order. This makes two versions of a file much easier to compare and keeps configuration files tidy, especially when several people edit them.