301 vs 302: which redirect to use
Permanent vs temporary redirects, what crawlers do with each, and how chains of mixed codes make a mess.
Technical SEO
Guides in this topic.
404s inside your XML sitemap
Sitemaps should list indexable 200 URLs. How 404s and redirects get stuck in the file, what Search Console does with them, and how to verify.
404 Errors in Google Search Console — Fix or Ignore?
Which GSC 404s need a restore or 301, which are scrapers and typos, and how to verify on the live page before you touch redirects.
How to Scan a Whole Website for Broken Links
Start from one URL, follow internal links, use the sitemap, pause, export. A practical whole-site workflow in Chrome without a desktop crawler.
Mixed content: HTTP assets on an HTTPS page
Browsers block or warn on http:// images, scripts, and links inside https:// pages. How to find them in Chrome next to 404s.
Redirect Chains: How to Find and Fix Them
A 301 through three hops is still a delay. How to see the full chain in Chrome, when to flatten it, and when a 302 is the wrong code.
What a soft 404 actually is
A 200 page that Google treats as missing. How it differs from a hard 404, where it shows up, and how to check the live template in Chrome.
Broken links in Yandex Webmaster
Yandex lists clicks to dead URLs from Browser data. How that report differs from a live Chrome scan, and how to use both on .ru sites.