JSON Formatter & Validator
Format, validate and minify JSON online. Pretty-print with 2 or 4 spaces, see exact error line and column, copy or download the result.
About the JSON Formatter & Validator
This free JSON formatter beautifies, validates and minifies JSON entirely in your browser. Paste any JSON — an API response, a config file, a log entry — choose 2-space or 4-space indentation and click Format to get perfectly indented, readable output. Nothing is uploaded to a server, so it is safe for API keys, tokens and production payloads.
Validation is precise: if the JSON is broken, the tool reports the exact line and column of the first error along with the parser message, so you can jump straight to the missing comma, stray trailing bracket or unquoted key instead of hunting through the whole document.
The Minify button strips every unnecessary space and newline to produce the smallest valid JSON, and shows the byte size before and after so you can see exactly how much you saved. Copy the result with one click or download it as a .json file.
How to Use the JSON Formatter & Validator
- 1Paste your JSON into the input box.
- 2Pick 2-space or 4-space indentation.
- 3Click Format to beautify, Minify to compress, or Validate to check syntax.
- 4Fix any error using the reported line and column.
- 5Copy the output or download it as a .json file.
Frequently Asked Questions
How do I validate JSON online?
Paste your JSON into the input box and click Validate. If the document is well-formed you'll see a green "Valid JSON" confirmation. If not, the tool shows the exact line and column where parsing failed plus the parser's message — typically a missing comma, an unescaped quote, a trailing comma or single quotes instead of double quotes.
Is it safe to paste sensitive JSON like API responses here?
Yes. Formatting, validation and minification all run in JavaScript inside your browser. The JSON is never transmitted to a server, never logged and never stored — it disappears when you close the tab. That makes the tool safe for payloads containing tokens, credentials or customer data.
What is the difference between formatting and minifying JSON?
Formatting (pretty-printing) adds indentation and line breaks so humans can read the structure easily — ideal for debugging and code review. Minifying does the opposite: it removes all insignificant whitespace to produce the smallest possible file, which is what you want for API responses and files shipped to production. Both outputs contain exactly the same data.
Why do I get "Unexpected token" errors in valid-looking JSON?
The most common causes are trailing commas after the last item, single quotes instead of double quotes, unquoted property names, comments (JSON does not allow // or /* */), and smart quotes pasted from Word or Slack. The line and column shown by the validator point to the first offending character.
Is there a size limit for the JSON I can format?
There is no hard limit — because everything runs locally, the practical ceiling is your device's memory. Documents of several megabytes format in well under a second on a modern machine. Extremely large files (hundreds of MB) may make the browser tab slow, so consider splitting those.