Free tool · { } JSON formatter & validator
Format, validate,minify JSON.
Paste an API response or a config file. Get a validity verdict, the error line if it is broken, a pretty version and a minified version — without your data leaving the browser.
Private by design: the page makes no network request with your content.
What it checks
Everything we would look at first on a client call.
Free, no sign-up, no email gate. If the report shows red, the fix is written next to it — and we are one click away if you would rather we did it.
- Validation with the error position and the surrounding text
- Pretty-print (2 or 4 spaces) and one-click minify
- Node count and size before/after
- Copy buttons for both versions
FAQ
Common questions
Is my data uploaded?
No. Open the browser network tab if you like — the page only loads its own assets.
Why does it say "Unexpected token"?
Usually trailing commas, single quotes instead of double, or comments — none are allowed in strict JSON.