spider-pig is a command line utility that takes a URL and retrieves all the local URL links on the page. It can also search for a CSS selector on each local URL to measure the impact of a CSS change.
<a href="test2.html">Duplicate Test</a>
<a href="root.html">URL to self</a>
<a href="mailto:firstname.lastname@example.org">Email link</a>
Can also act as a live-DOM CSS search across multiple files (find all the templates that are using the CSS selector I want to change). If I’m worried about changing code in a CSS selector, I’ll use this tool to search for instances of the selector across my project.