Linkchecker is an application to verify your web links. Features include 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, restrict link checking with regular expression filters for URLs, proxy support, and username or password authorization for HTTP, FTP, and Telnet.