In brief: A crawler is a program that automatically visits URLs, reads their content and follows links. Search engines use it to discover and repeatedly check pages.
How I use a crawler in practice
I address crawlers from the simplest test to more expensive diagnosis. First, I try to reproduce the problem, separate a content error from a template error, and find out how many addresses it affects. I deploy the fix on a small sample, check the status and internal links, and only then extend it.
What to watch out for
A technical solution should not conceal weak content. A crawler can remove an obstacle, but it will not create a reason for someone to visit or trust the page. I therefore assess a fix together with the URL’s role, internal linking and next step.
Questions for decision-making
- What exactly does the server return, and what does a person see on an important URL?
- Is it an isolated error or a pattern in a shared template?
- What is the impact on discoverability, use or conversion?
- How will we test the change before a full rollout?