This tool collapses formatted JSON into a single compact line, validating it along the way. Because the input is parsed rather than pattern-matched, a missing brace, a trailing comma or an unquoted key is reported as a syntax error instead of producing broken output — which makes it a quick validity check as well as a size reducer. The data itself is unchanged: key order, nesting, number precision and Unicode escapes all survive intact. Compact JSON matters when you are pasting into an environment variable, a single-line config field, a curl command or an HTML data attribute, where line breaks are awkward or outright invalid.
Free, fast, and runs entirely in your browser — no signup, no upload to a server.