LinkChecker is a free, GPL licensed website validator. LinkChecker checks links in web documents or full websites. Check websites and HTML documents for broken links. Features recursive and multithreaded checking and site crawling output in colored or normal text, HTML, SQL, CSV, XML or a sitemap graph in different formats HTTP/1.1, HTTPS, FTP, mailto:, news:, nntp:, Telnet and local file links support restriction of link checking with regular expression filters for URLs proxy support username/password authorization for HTTP and FTP and Telnet honors robots.txt exclusion protocol Cookie support HTML5 support HTML and CSS syntax check Antivirus check Different interfaces: command line, GUI and web interface ... and a lot more check options documented in the manual page.