What is link rot?
GET https://example.com/blog/2021/old-post HTTP/1.1 404 Not Found
Where links go to die.
Redesigns and migrations
URLs change and the old ones are not redirected.
Deleted content
A page is removed with no replacement.
Expired domains
A domain lapses and the whole site vanishes or changes hands.
Shut-down services
A shortener, a file host or an app closes, and every link it created stops working.
Typos
A link was wrong from the start.
Access changes
A document moves behind a login or to a different permission.
How to keep links alive.
Keep URLs stable
Choose addresses that don't depend on dates, categories or tools you may change.
Redirect when you move
Send every old URL to its replacement with a 301.
Check regularly
Run lists of important links through a status checker and fix the ones that fail.
Where link rot is worst.
A link on paper or on packaging can't be corrected afterwards. Point printed links and QR codes at a short link you control, so the destination can be fixed whenever the page moves.
Common questions
How do I find broken links? +
Run a list of URLs through the HTTP status checker, which reports the status code of up to ten at once.
Do short links cause link rot? +
They add a dependency: if the service closes, its links stop working. They also help, because on an account-based service you can edit the destination when a page moves.
What does a 404 mean? +
The server is reachable but nothing exists at that address. The HTTP status codes page lists the others.
Is link rot bad for SEO? +
Broken internal links waste crawl effort and create poor experiences, and links from other sites to a page that no longer exists stop passing value.