The false positive that wastes everybody's time
Run a typical link checker over a page with a few external links and it reports several as broken. You open them one by one, and every one loads perfectly. An hour gone, nothing fixed, and you trust the tool a little less.
The cause is bot protection. Cloudflare and similar services return 403 or 429 to anything that looks automated while serving the same page normally to a browser. That says nothing at all about whether the link works — only that the server declined to talk to a robot.
Reporting those as broken is the single biggest usability failure of free link checkers. Here they are labelled bot-blocked and kept separate from links returning a genuine 404, so the broken list is one you can act on without verifying it first.
Why broken links matter, and how much
For visitors, more than most SEO factors. Someone reading an article, clicking a source and hitting a 404 loses trust in the page — and unlike a ranking problem, the damage happens to the person already reading.
For rankings, less than commonly claimed. Google has said repeatedly that a few broken outbound links do not hurt a site directly; the web decays and it expects that. Broken internal links matter more, because they waste crawl budget and strand pages that nothing else links to.
The realistic priority: fix broken internal links promptly, since those are entirely within your control and indicate structural problems. Review broken external links periodically — a dead source under a factual claim undermines the claim itself.
What the verdicts mean
Broken means a genuine 404, 410 or 5xx. These need attention: update the link, point it somewhere current, or remove it. For internal links, the destination may simply have moved without a redirect.
Bot-blocked means 403, 429 or 401. The server refused an automated request. Check by hand if it matters, but the link is probably fine — and a 401 usually means a page that legitimately requires a login.
Redirects means the link works but arrives via a hop. Not broken, and worth updating to the final address if the destination has moved for good. No response means a timeout — the host may be slow rather than gone, so it is reported as unproven rather than dead.