Website Tools
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.
JustChecker builds tools that respect your data - this one never leaves your browser.
Frequently Asked Questions
No - this tool runs entirely in your browser using JavaScript. Your JSON is never transmitted anywhere.
It catches syntax errors like missing commas, unmatched brackets/braces, trailing commas, and improperly quoted keys or strings - anything that would make the JSON fail to parse.
Valid JSON only means the syntax is correct - it doesn't check whether the data itself matches what your application or API expects (that would require a schema validator).