Dead Link Checker

A dead link checker crawls through URLs you feed it and reports every link that returns a status code in the 4xx or 5xx range — most commonly 404 (Not Found) and 410 (Gone). It also often flags redirects like 301, 307, and 308, which lets you separate truly broken links from ones that simply need a redirect update. I use this to scan a site’s entire internal link structure, but many tools also check external links, so you can catch broken outbound references to resources you don’t control.

When I run a site audit, I start with a tool like the W3C Link Checker because it’s standards-based and free. It scans not only HTML <a> tags but also anchors, images, CSS references, and other embedded objects. That breadth is important: a broken image in a product page might not be a link, but it damages the user experience just as much. For a larger site, I switch to a dedicated checker that supports CSV export, so I can triage the results by page priority. Exporting a list of all broken internal links, sorted by the number of incoming links pointing to the broken page, lets me decide which 301 redirects to set up first. That’s where the value shows: fixing a 404 on a page that has 50 inbound links preserves more link equity than patching a page with only two.

I also lean on [Google Search Console](/seo-audit/) for ongoing monitoring. It catches server errors and 404s that its crawler encounters, but it doesn’t scan every page the way a standalone checker does. For a deep one-off audit, nothing beats a tool that crawls your whole site and reports every broken link, internal and external, in one go.

The biggest blind spot: most free dead link checkers cannot evaluate JavaScript-rendered links. If your site loads navigation links via JavaScript, those <a> tags may not exist in the raw HTML the tool receives. I once ran a checker on a client site that used a JavaScript framework for its mega-menu, and the tool reported zero broken links. I knew that was wrong. When I manually inspected the rendered page, I found three broken internal links in the menu. The tool never saw them. So if your site relies heavily on JavaScript for navigation, you need a checker that can execute JavaScript, like Screaming Frog or a custom script using Puppeteer. Most free online checkers cannot do that.

Another awkward scenario: checking a large site with thousands of pages. Free tools often impose a page limit — 1,000 or 3,000 URLs — and some enforce a crawl delay that makes the process painfully slow. I ran into this on a 10,000-page e-commerce site. The free checker I used crawled only 2,000 pages before timing out. I had to split the crawl into batches, which defeated the purpose of a single audit. Paid tools like Ahrefs handle larger crawls, but they cost money. For a one-person operation, that might not be justified.

External links are another pain point. When a checker reports a broken external link, it might be a temporary glitch on the remote server — a 503 or a 429 that resolves in a few minutes. The tool does not retry. I learned to treat external link failures as potential false positives. I check a sample manually by re-requesting the URL a few hours later. If the link is still broken, then I act. Also, some sites block the checker’s IP address, so you get a connection error that looks like a dead link when it’s actually a firewall issue. I always verify a few of the reported broken links by visiting them in a browser first.

If I need a quick, free, and reliable check for a small site, I use the W3C Link Checker. It’s not the prettiest interface, but it is thorough and respects the robots.txt file, so it won’t hammer your server. For a single page or a small domain, it’s my first choice. For a larger site where I want to manage the crawl and export results, I turn to a dedicated tool like Dead Link Checker (the domain deadlinkchecker.com). It supports CSV export, has a simple interface, and lets you exclude certain link patterns. I have used it for sites up to 5,000 pages without issues.

When I want to integrate broken-link checking into a broader [technical SEO](/technical-seo/) workflow, I use either Google Search Console for ongoing monitoring or a desktop crawler like Screaming Frog (not free, but worth it). Screaming Frog can render JavaScript, supports custom extraction, and exports every detail you need for a redirect mapping. I pair it with a [301 redirect](/301-redirect/) plan to map old URLs to new ones. For outreach purposes — finding broken links on other sites that point to your content — Ahrefs’ Broken Link Checker is excellent. It scans the web for backlinks to your site and identifies which ones are broken, so you can ask the linking site to update the link.

I also check [sitemap](/sitemap/) regularly to ensure that URLs I submit are not returning 404s. A broken link in your sitemap is a signal to Google that your site is poorly maintained. If you have a lot of pages, consider using a tool that checks the [canonical URL](/canonical-tag/) as well: sometimes a 404 on a canonicalised page is harmless, but it can still confuse users. The key is to match the tool to the job size. For a single urgent fix, a free online checker is fine. For a recurring audit, invest in something that handles JavaScript and exports clean data.