JSON Formatter

A JSON Formatter takes cramped or messy JSON and rebuilds it with clean indentation so you can actually read it. Paste your JSON, pick an indent of 2 spaces, 4 spaces or a tab, and the formatted result appears live. It is free, runs in your browser, and nothing is uploaded.

How the JSON Formatter works

Paste JSON into the box, or drop in a file, and the formatted version builds as you type. You choose the indent style, and a stats line under the result shows the total object keys, the maximum depth and the input and output sizes, so you can see the shape of the data at a glance.

1. Paste your JSON or drop a .json file into the box.
2. Pick an indent: 2 spaces, 4 spaces or a tab.
3. Turn on key sorting if you want keys in alphabetical order at every level.
4. Read the formatted output and the stats line below it.
5. Copy the result or download it as a file.

Key sorting applies at every level of the document, not just the top. Nested objects get the same alphabetical treatment, which makes two versions of a file much easier to compare side by side. If the JSON will not parse, the box shows the parser error message instead of a result, so you know the input needs a fix before formatting can happen. For a closer look at an error, the JSON Validator shows the line and column as well.

When a JSON Formatter earns its keep

API responses are the classic case. A payment gateway, a weather service or your own test server hands back one long line of JSON, and finding one field inside it means squinting at a wall of brackets. Formatted with a clear indent, the same response reads like an outline. You can follow the nesting, spot the field you need and see what sits next to it.

Config files are the second case. Settings for an app, a build tool or a deployment often live in JSON, and a misplaced level of nesting changes what the file actually says. Readable indentation turns a config file from a guessing game into something you can check line by line, and sorted keys make a diff between two versions short and honest.

Learning and teaching count too. Students meeting JSON for the first time understand it faster when the structure is visible, and support teams paste formatted output into tickets so the next person reads the same shape they saw.

JSON Formatter rules and honest limits

This formatter parses your JSON and rebuilds it, and that method carries one limit worth knowing. Browsers read JSON numbers as standard double precision values, so a whole number longer than about 16 digits can lose precision when it is parsed and written back. If your data carries very long integers, such as database IDs, check those figures in the output before you rely on them.

Duplicate keys are a second quiet trap. JSON allows the same key twice in one object, and standard parsing keeps the last value. The formatted output shows that last value, and the earlier one is gone. The formatter does not flag duplicates, so if you suspect them, that check is yours to make.

Comments and trailing commas are not valid JSON, and this page treats them that way. Paste JSON with a comment in it and you get a parse error, not a quietly repaired file. The same goes for single quoted strings and unquoted keys. If you want the one line version instead, the JSON Minifier strips the spacing back out, and the JSON Viewer turns the same data into a collapsible tree.

Your JSON stays in your browser

The formatting runs on your device. Your JSON is not sent to a server, not stored by ToolPeko and not read by anyone here. Close the tab and the text goes with it. There is no account, no daily cap and no run limit. A two line snippet and a full API dump get the same treatment.