Regex Editor & Tester

Matches custom HTML comment blocks delimited by <!--sec: and #--> markers, capturing the content between them. The \s* allows optional surrounding whitespace, while [\s\S]*? non-greedily captures everything inside, including newlines. This pattern is useful for extracting marked sections or hidden content blocks from HTML documents, often in build tools, static site generators, or templating systems that use custom comment-based directives.