Free JSON Formatter & Validator
Format, minify and validate JSON in your browser. Paste your data to get clean output and clear error messages.
- Free, no signup
- Data stays in your browser
- Errors show line and column
How to use JSON Formatter
- Paste your JSON into the input editor.
- Choose Format to pretty-print, Minify to compress, or Validate to check the syntax.
- If there is an error, fix it at the line and column shown.
- Copy the output or download it as a .json file.
Features
- Pretty-print with 2 spaces, 4 spaces or tabs
- Minify to the smallest valid form
- Validation that reports the line and column of the first error
- Optional alphabetical key sorting
- Copy or download the result as a .json file
- Runs locally — API responses and config files are never uploaded
What can you use JSON Formatter for?
JSON is the standard format for exchanging structured data between apps and APIs, but unformatted JSON is hard to read. This formatter pretty-prints, minifies and validates JSON so you can quickly spot errors and share clean output.
APIs and config files return JSON without line breaks or indentation, which is efficient for machines but unreadable for people. Formatting adds consistent indentation so nested objects and arrays are easy to scan, while validation flags the exact syntax error — a missing comma, an extra bracket — that would otherwise cause a parser to fail silently.
- Pretty-printing a minified API response to inspect its structure during debugging.
- Validating a config file or payload before deploying it, to catch syntax errors early.
- Minifying JSON before sending it over the network to reduce payload size.
- Cleaning up JSON before pasting it into documentation or a bug report so reviewers can read it.
Tips for better results
- Run Validate first on unfamiliar JSON — it's faster than scanning by eye for a missing comma or bracket.
- Minify only for machine-to-machine use (APIs, storage); keep the formatted version for anything a person needs to read.
- Watch for trailing commas — valid in some languages, but invalid in strict JSON and a common cause of parse errors.
- Double vs single quotes matter: JSON requires double quotes around keys and string values.
Frequently asked questions
Is this JSON formatter free?
Yes, formatting, minifying and validating JSON is completely free.
Does the JSON formatter upload my data?
No. All formatting and validation happens locally in your browser.
Can I minify JSON as well as format it?
Yes, use the Minify button to compress JSON, or Format to pretty-print it.
Why does validation fail on JSON that looks correct?
The most common causes are trailing commas, single quotes instead of double quotes, or an unescaped quote inside a string — the validator points to where parsing breaks.
Is minified JSON functionally different from formatted JSON?
No, whitespace doesn't change the data — minifying only removes the line breaks and indentation to reduce file size.
Why does my JSON fail validation?
The usual causes are trailing commas, single quotes instead of double quotes, unquoted keys and comments. Strict JSON allows none of these, so remove them and validate again.
Does formatting change my data?
Formatting only changes whitespace and, if you turn it on, the order of keys. One caveat: numbers larger than 9,007,199,254,740,991 lose precision when parsed in the browser, so keep very large IDs as strings.