A website crawler is a tool that visits your pages the way a search engine bot does, following links and recording information about every URL it finds. Crawlers reveal broken links, redirect chains, duplicate titles, missing meta descriptions, orphan pages, slow pages and many other technical issues that are hard to spot manually.
What Crawlers Check
| — | — |
|---|---|
| Status codes | 404 errors, 5xx errors, redirects |
| Titles and descriptions | Missing, duplicate, too long or short |
| Headings | Missing or multiple H1s |
| Indexability | Noindex tags, robots.txt blocks |
| Canonicals | Missing, conflicting or pointing to redirects |
| Internal links | Broken links, orphan pages, deep pages |
| Images | Missing alt text, large files |
| Structured data | Errors (in some tools) |
Types of Crawler Tools
| — | — |
|---|---|
| Desktop crawlers | Installed software, flexible, often with free limits |
| Cloud crawlers | Run online, schedule regular crawls, team features |
| Built-in tools | Bing Site Scan and SEO tool audits |
| Plugin-based checks | Limited checks within WordPress |
How to Run a Crawl
- Enter your homepage URL
- Set crawl limits and respect server resources
- Choose whether to crawl subdomains, images and JavaScript rendering
- Start the crawl and wait for completion
- Export results or review built-in reports
Prioritising Issues
| — | — |
|---|---|
| Medium | Redirect chains, duplicate titles |
Focus on issues affecting important pages and users first.
Using Crawl Data
- Fix broken links or redirect removed pages
- Update internal links to final URLs
- Write unique titles and descriptions
- Find orphan pages and link to them
- Reduce click depth for important content
- Compress large images
JavaScript Rendering
Some sites rely on JavaScript to show content. Many crawlers can render JavaScript to see content as browsers do, though this uses more resources. Compare rendered and raw HTML if content seems missing.
Crawl Responsibly
Large crawls can strain small servers. Limit crawl speed, crawl during quieter times and avoid crawling sites you do not own aggressively.
How Often to Crawl
- Small sites: monthly or quarterly
- Large or frequently updated sites: weekly or scheduled cloud crawls
- After migrations, redesigns or structure changes
Common Mistakes
- Trying to fix every warning without prioritising
- Crawling staging sites that block bots and misreading results
- Ignoring crawl configuration, leading to incomplete data
Frequently Asked Questions
Are there free crawlers?
Yes, many offer free versions with URL limits.
Do crawlers see my site exactly like Google?
They simulate search engine crawling, but Google’s systems are more complex.
How long does a crawl take?
From minutes for small sites to hours for large ones.
Can crawling harm my site?
Aggressive settings can overload weak servers; use sensible speeds.
Conclusion
Website crawlers reveal technical problems that hide beneath the surface. Run regular crawls, focus on errors affecting important pages, fix links, redirects and metadata, and use the insights to keep your site healthy and search-friendly.
