JSON Validator
Instantly check whether your JSON is valid, right in your browser.
Paste your JSON below to instantly check whether it's valid - entirely in your browser, nothing is sent to our servers.
JSON is stricter than the JavaScript it is based on: property names and strings must use double quotes, trailing commas and comments are not allowed, and values such as undefined or NaN are invalid. The validator checks your input against that strict standard and, when it fails, shows the browser parser's error message, which usually names the unexpected character and its position. Typical uses are checking an API response, a webhook payload or a configuration file such as package.json before relying on it. JustChecker builds tools that respect your data - this one never leaves your browser.