RankForge is a free, browser-based SEO crawler. It crawls a site, diffs the crawl against the sitemap to surface orphan pages that nothing links to, maps internal links and anchor text, and reports broken internal and outbound links. Everything runs in the browser with no account, no install and no paid tier, so a technical audit that normally needs a desktop crawler takes a couple of minutes from any machine.
I kept hitting the same wall on small sites: the pages that never rank are the ones nothing links to, and every tool that finds them is a paid desktop crawler. RankForge does that one job in the browser and keeps it free.