JSON validator & formatter

Paste JSON to check it instantly. See VALID, or the exact line and column of the error with a short hint — then copy the prettified result. Nothing is uploaded.

Your JSON
Mode
Indent

Everything runs in your browser. No upload, no sign-up.

How it works

STEP 1

Paste your JSON

Drop in an API response, config file or any JSON. It is checked right in your browser — nothing leaves your device.

STEP 2

See valid or the exact error

A green badge confirms valid JSON. Otherwise you get the precise line and column, the offending character and a plain-English hint.

STEP 3

Format & copy

Valid JSON is pretty-printed with your chosen indent. Copy it with one click, or minify it down to a single line.