JSON Formatter & Validator — Free Online
Format, validate and minify JSON instantly in your browser. Pinpoints the exact error line. No upload, no length limit.
How it works
Paste messy JSON and get a clean, indented, readable version back. If the JSON is broken, the validator tells you exactly which line and character position the parser gave up on — which is the part that actually saves time.
It also does the reverse: minify JSON to strip whitespace before you ship it, or sort keys to make diffs smaller. All of it runs in your browser, so pasting a sensitive API response is safe.
How to use it
- Paste your JSON into the left box, or click Sample to see how it works.
- Click Format to pretty print, or Minify to compress it.
- Errors show up as a red banner with the line and column number.
- Copy the result, or download it as a .json file.
Why this runs in your browser
Every tool on this site runs 100% in your browser. Your files are never uploaded to any server. That means no upload wait, no third party holding a copy of your data, and it keeps working even if your connection drops.
Frequently asked questions
Does this send my JSON to a server?
No. Parsing and formatting use your browser's built-in JSON object. Nothing is transmitted anywhere, so it is safe for production data and credentials.
How accurate is the error reporting?
It reports the position where the built-in parser failed. For common mistakes like a trailing comma or a missing quote, that position is usually right at the problem.
Is there a size limit?
No imposed limit. Very large documents (tens of megabytes) may make the editor sluggish, but they will not be rejected.
Can it convert JSON to other formats?
Not here yet. JSON to CSV and JSON to YAML converters are on the roadmap.
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