# Broken Link + Decay Scanner — find every 404 your page points at

Outbound links decay. The average 5-year-old article has 10-25% of its external references dead, redirecting to parked domains, or quietly 302-ed into spam. This tool fetches every outbound link in parallel and reports the damage.

Author: J.A. Watte
Published: April 22, 2026
Source: https://jwatte.com/blog/blog-tool-broken-link-decay-scanner/

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Link rot is the quiet enemy of long-tail SEO. A blog post written in 2020 that was topically authoritative at publication often has 20%+ of its citations dead by 2026. The text still reads fine to a user, but the trust signal dies: a well-cited article citing dead sources becomes a well-written article with broken claims.

Google's quality algorithms track this indirectly. Pages with high rates of outbound 404s and 5xxs are treated as maintenance-neglected and deprioritized — not because the links themselves are penalized, but because stale links correlate with stale content overall.

[The Broken Link + Decay Scanner](/tools/broken-link-decay-scanner/) fetches every outbound link in parallel (throttled, polite) and reports:

## What it finds

- **4xx errors** — dead pages (404, 410, 403, 401)
- **5xx errors** — server failures (500, 502, 503)
- **Redirect chains** — 301/302 chains, including whether the final target is relevant
- **Target mismatch** — a link that says "see [original study]" redirecting to a domain-parking page
- **Timeouts** — links that don't resolve within 10s
- **DNS failures** — host no longer resolves (domain expired)
- **Protocol issues** — HTTP in an HTTPS page (mixed content)
- **Suspicious redirects** — chain endpoints at known link-squatting domains

Each finding includes the anchor text, the original URL, the final resolved URL, the status code at each hop, and a severity rating (CRITICAL for 404/DNS-failure, WARNING for redirect chain of 3+, INFO for single-hop 301).

## Why "decay" as a metric matters

The scanner doesn't just count 404s. It computes a **decay score** — percentage of outbound links that no longer resolve to their original destination. A page at >15% decay has content-maintenance debt; >30% is abandoned.

That metric is the fastest way to prioritize which old pages to revive vs. retire. An old post with 5% decay is earning its traffic — fix the few broken links and move on. A post at 50% decay is probably topically obsolete and a deadweight crawl-budget tax.

## What to do when you find them

For each broken outbound link:
1. **Remove** if the link was incidental and the original claim stands without it
2. **Replace** with the Wayback Machine URL if the original URL is gone but content exists
3. **Update** to the current best-available source on the same topic
4. **Remove the claim** if no verifiable source exists any more

Many sites do a "bulk nofollow" on broken links. That's wrong — it hides the problem from auditors without fixing the user experience.

## How to use it

1. Go to [/tools/broken-link-decay-scanner/](/tools/broken-link-decay-scanner/)
2. Paste a URL
3. Tool extracts every outbound link and tests in parallel (~10 at a time)
4. Read the decay report + per-link status
5. Export CSV for bulk remediation

Typical runtime: 10-60 seconds depending on link count.

## Related reading

- [Canonical & Redirect Graph](/tools/canonical-redirect-graph/) — site-wide redirect visualization
- [Internal Link Equity Flow](/tools/internal-link-equity-flow/) — PageRank flow through your internal links
- [Content Decay Audit](/tools/content-decay-audit/) — identify stale posts by age × traffic

## Fact-check notes and sources

- **Link rot research:** [Harvard Law School Library — Perma.cc link-rot study](https://perma.cc/).
- **Google quality signals on outbound links:** [Google Search Quality Rater Guidelines](https://services.google.com/fh/files/misc/hsw-sqrg.pdf).
- **Wayback Machine:** [archive.org/wayback](https://web.archive.org/).
- **Mixed content (HTTP in HTTPS):** [MDN — Mixed content](https://developer.mozilla.org/en-US/docs/Web/Security/Mixed_content).

_This post is informational, not SEO-consulting advice. Mentions of Google, Harvard Law School, the Internet Archive, and similar products/institutions are nominative fair use. No affiliation is implied._


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