Technical SEO
Indexing, sitemaps, canonicals, structured data, hreflang and lossless migrations.
Crawl budget: when it really matters and how not to waste it
What crawl budget is, why it mainly concerns large or highly dynamic sites, and which technical waste uses up crawler visits without any real benefit.
Crawling, rendering and indexing: how a search engine reads a site
The three stages a search engine uses to discover, interpret and store pages: what happens in each one and where common websites tend to get stuck.
Changing domain without losing traffic: the migration plan
How to move a site to a new domain: URL inventory, redirect map, switchover day, notifying search engines and the checks to run in the weeks that follow.
Faceted navigation: filters and parameters without a URL explosion
How to handle catalogue filters and sorting without creating millions of URLs: which combinations to index, which to block and which techniques to use.
Hreflang: how to connect the language versions of a site
How hreflang annotations work: language and country codes, return links and x-default, plus the most common mistakes and a method for checking them.
IndexNow and engine notifications: reporting changes right away
How the IndexNow protocol works, how to set up the key, when it is worth using and what it cannot do compared with well-kept sitemaps and internal links.
Internal links, click depth and orphan pages
How internal links drive crawling and page importance: click depth, orphan pages, link text, menus and related modules, with a method for checking.
JavaScript sites and SEO: client-side, server-side and static
Choosing between client-side rendering, server-side rendering and static pages for a JavaScript site, and the mistakes that hide content from engines.
Meta robots and X-Robots-Tag: noindex, nofollow and other rules
How to use meta robots and the X-Robots-Tag header to control indexing, links and snippets, including on PDFs and images, while avoiding common conflicts.
Mobile-first indexing: parity between mobile and desktop
What it means for search engines to index the mobile version of a site, which differences from desktop cause lost content, and how to check for parity.
Multilingual sites: subfolders, subdomains or country domains
Comparing subfolders, subdomains and country-code domains for a site in several languages, and why automatic redirects based on IP or browser are a risk.
The page indexing report: how to read the statuses
How to interpret the report on non-indexed pages in webmaster tools: which statuses are normal, which signal a real problem and what to do about each.
Pagination: long lists that search engines can actually crawl
How to handle categories and archives split across pages: URLs for later pages, canonicals, links, infinite scroll and «load more» buttons done properly.
Redesign and CMS change: the SEO checklist before launch
What to check when rebuilding a site or changing CMS: comparing old and new versions, templates, lost content, performance and testing in staging.
Redirect chains and loops: how to find and flatten them
Why multi-hop redirects slow down users and crawlers, how they build up after successive migrations, how to detect them with a crawler and how to flatten them.
301, 302, 307 and 308 redirects: which to use and when
The differences between permanent and temporary redirect codes, how browsers and search engines read them and why to avoid meta refresh and JavaScript.
Rel canonical: how to point to the main version of a page
How the canonical tag works, why it is a hint rather than an order, which signals confirm or contradict it and the most frequent technical mistakes.
Removed pages: 404, 410, soft 404 and when to use a redirect
Handling deleted pages or out-of-stock products: 404 versus 410, what soft 404s are, when to redirect and how to build an error page that helps.
The robots.txt file: syntax, precedence and mistakes to avoid
How to write a correct robots.txt: user-agent, Disallow, Allow, wildcards, rule precedence and the mistakes that accidentally block entire websites.
5xx errors, 429 and maintenance: how crawlers react
What happens to crawling when the server returns 500, 503 or 429, how to handle scheduled maintenance and why firewalls and CDNs can block search engines.
Server logs for SEO: what crawlers really do on your site
How to read access logs to see which pages crawlers visit, how to spot fake Googlebots with reverse DNS lookups, and which questions the data can answer.
Sitemap indexes for large sites: split, monitor, scale
How to organise sitemaps on a site with many pages: sitemap index, splitting by page type, image and video sitemaps, and diagnosis by section.
Structured data over time: testing, monitoring and regressions
Keeping structured data valid after the first release: errors and warnings, automated tests in the build, search engine reports and page consistency.
Technical duplicate content: www, trailing slash, case and HTTP
The URL variants that duplicate every page without anyone noticing: protocol, www, trailing slash, letter case, index.html. How to find and unify them.
XML sitemaps: structure, limits and what to actually include
How to build a useful XML sitemap: format, size limits, correct use of lastmod, which URLs to include or exclude and how to submit it to search engines.