JSON Formatter & Validator
Validate and pretty-print JSON with custom indentation. Everything happens locally.
Paste minified or malformed JSON and get it validated and pretty-printed with your choice of indentation, or catch a syntax error with its exact location highlighted. Useful for debugging an API response that came back as one long line, cleaning up a config file, or checking whether a payload is valid JSON before sending it. Formatting and validation both run locally with no upload.
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How it works
- 01
Paste your JSON.
- 02
Choose an indentation style.
- 03
Copy the formatted, validated output.
Details
- Category
- Developer & data
- Formats
- JSON
- Runs
- In your browser
- Files uploaded
- No
- Cost per run
- Free
- Sign-in
- Not required
- Works offline
- Yes, once loaded
Last updated 2026-08-03
Common questions
What happens if my JSON is invalid?
The formatter highlights the exact position of the parse error so you can find and fix it quickly.
Can I choose the indentation size?
Yes - pick 2 spaces, 4 spaces, or tabs for the pretty-printed output.
Can I minify JSON with this too?
Yes - collapsing to a single line with no whitespace is one of the formatting options.
Does it upload my JSON?
No - validation and formatting happen locally.