Free software program for checking a website for broken links, internal and external

Newest list and explicitly open source: https://www.testingexcellence.com/9-open-source-link-checking-tools/

… but the first thing it lists is last updated in 2004! http://htcheck.sourceforge.net/

https://www.wpuniversity.com/blog/5-tools-find-broken-links

The latest version of that; apparently still with expired dependencies: https://github.com/Nick-Rivera/broken-link-checker

Not updated in 6 or 7 years https://github.com/k4ml/palu