JSON Formatter
Paste messy or minified JSON and get clean, indented output instantly. Errors are pinpointed to the line and column, and your data never leaves the browser.
- Runs in your browser
- No sign-up
- Free to use
How to use JSON Formatter
- Paste your JSON into the input editor, or choose Open file to load a .json file from your device.
- Pick an indentation style (2 spaces, 4 spaces or tabs) and tick Sort keys if you want properties in alphabetical order.
- Select Format to pretty-print, or Minify to strip all whitespace.
- Copy the result or download it as a .json file.
JSON Formatter features
Line-accurate error reporting
If the JSON is invalid, the offending line is highlighted in the gutter and the message explains what the parser expected.
Three indentation styles
Switch between 2 spaces, 4 spaces and tabs to match your project's code style.
Alphabetical key sorting
Sort object keys recursively to make two payloads easy to compare in a diff.
One-click minify
Collapse formatted JSON back to a single line for config values, query strings or network payloads.
Structure summary
See at a glance whether the root is an object or array, how many keys it holds and how deeply it nests.
Works offline after loading
Parsing uses your browser's native JSON engine, so large documents format quickly and privately.
When to use JSON Formatter
- Reading an API response that arrived as one long line.
- Cleaning up a configuration file before committing it to version control.
- Finding the missing comma or stray quote that makes a payload fail to parse.
- Sorting keys in two JSON documents so a text diff shows only real differences.
- Shrinking JSON before embedding it in an environment variable or HTML attribute.
JSON Formatter FAQ
Is my JSON sent to a server?
No. Formatting, validation and minifying all run in your browser using JavaScript. The text you paste is never transmitted or stored.
Why does the formatter say my JSON is invalid?
JSON is stricter than JavaScript object syntax. Common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments, and values such as undefined or NaN. The error message shows the line and column where parsing stopped.
Does formatting change my data?
Whitespace and, optionally, key order change; values do not. One exception is very large integers: numbers beyond 9,007,199,254,740,991 cannot be represented exactly in JavaScript and may be rounded. Keep such identifiers as strings.
How large a file can I format?
There is no fixed limit. Documents of several megabytes format in well under a second on a typical laptop; very large files are limited only by your device's memory.
What is the difference between formatting and validating?
Formatting rewrites valid JSON with consistent indentation. Validating only checks whether the text is valid JSON. This tool validates as you type and formats on request.
What JSON formatting does and why it matters
JSON (JavaScript Object Notation) is the most common format for exchanging data between web services. Machines do not care about whitespace, so APIs usually send JSON minified on a single line to save bytes. That is efficient for the network but nearly unreadable for a person trying to find one field among hundreds.
A formatter parses the text into a data structure and writes it back out with one property per line and consistent indentation. Because the text has to be parsed first, a formatter is also a strict syntax check: if the document cannot be parsed, it cannot be formatted, and the position where the parser gave up is usually within a character or two of the actual mistake.
Two-space indentation is the most common convention in JavaScript projects, four spaces are typical in Python and Java ecosystems, and tabs let each reader choose their own width. Sorting keys has no effect on meaning, since JSON objects are unordered, but it makes documents deterministic, which helps with code review and caching.