A link checker is a service or software tool that is used for checking or verifying broken hyperlinks in a website or a Web page. It allows website owners to identify dead or broken links and thus avoid linking to invalid Web pages.

There are different link checkers available: some are free and some are commercial. There are also online and offline versions available. Simple link checkers check for broken links in the Web pages of a website, whereas advanced ones also check for external links to other websites. Almost all link checkers are recursive in nature and can perform site crawling either automatically or when the user initiates it. Some link checkers come with additional features like antivirus checks, syntax checks, additional information about the links used, etc. Some link checkers also provide a browser plugin or add-on support.