HTML Purifier is installed successfully.
HTML Purifier is a Framework, so doesn't have an index page.
HTML Purifier is a standards-compliant HTML filter library written in PHP.
HTML Purifier will not only remove all malicious code (better known as XSS) with a thoroughly audited, secure yet permissive whitelist, it will also make sure your documents are standards compliant, something only achievable with a comprehensive knowledge of W3C's specifications.