The Broken Link Checker is a free tool from Ergora for site owners that fetches every link on a page and lists the ones that are broken or redirect.
Enter a page address. We find the links on it and fetch each one to see whether it still loads, then list the broken ones and the ones that redirect on the way.
Free, no sign-up. We fetch public pages only and store nothing.
A visitor who clicks a link and hits an error page is less likely to stay, and a page full of broken links tells search engines the site is not well looked after. Both cost you, and both are easy to miss from the inside.
Pages get renamed, other sites go offline, a product is discontinued. A link that worked when you wrote it can break months later with no warning, which is why checking the important pages now and then is worth the minute.
A link that returns an error or a 4xx or 5xx status, such as 404 Not Found or 500 Server Error, or one that does not respond at all. This check treats any of those as broken.
Up to 25 on the page, so it stays fast. Run it on your important pages one at a time. For a crawl of every page on a site, use a dedicated site auditor instead.
Not as a direct ranking penalty, but they waste the crawl budget Google spends on your site, frustrate visitors, and add up to a signal that the site is neglected. Fixing them is low effort for a clear gain.
A redirect still reaches a working page, just through an extra hop. A broken link reaches nothing. This check lists both, because redirects are worth tidying even though they are not broken.
Some servers block automated requests or need a login, so the link may be fine for a person even though the check could not load it. When that happens, open it yourself to confirm.
This is a one-off check. In Ergora the SEO specialist in the Content pack runs checks like this across every page, connects Search Console, and turns what it finds into fixes, briefs and posts that help you rank, week after week.