What Is Technical SEO? Everything It Covers and How to Check Yours

In short: technical SEO = crawlability + indexability + site speed + structure + structured data. Get it wrong and everything else underperforms.

What technical SEO covers

Crawlability

Can search engines reach every page that matters? This includes robots.txt rules, internal linking, XML sitemaps, crawl depth, server response codes and avoiding crawl traps such as infinite calendar pages or faceted filters that generate millions of URLs.

Indexability

Of the pages crawled, which should be stored and shown? Canonical tags, noindex directives, duplicate content handling, pagination and parameter management all decide this. Many sites have thousands of low-value pages indexed and their best pages missing — the gap between “crawled” and “indexed” in Search Console tells the story.

Rendering and JavaScript

Modern sites often load content with JavaScript. Google can render JavaScript, but with delays and limits. Content that only appears after user interaction, or that depends on failed scripts, may never be indexed. Server-side rendering, pre-rendering or simply keeping key content in the HTML avoids the problem.

Site speed and Core Web Vitals

Google measures three user-experience metrics from real visitors: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (stability). Targets are 2.5 seconds, 200 milliseconds and 0.1 respectively. Image delivery, render-blocking CSS and JavaScript, fonts, caching and third-party scripts are the usual culprits.

Site architecture and URLs

A logical hierarchy — home → category → sub-category → page — with descriptive URLs and sensible internal linking helps both users and crawlers, and it distributes authority to the pages you want to rank. Orphan pages (no internal links) and very deep pages are common problems on older sites.

Structured data

Schema markup (Organization, LocalBusiness, Product, Article, FAQ, Breadcrumb and so on) describes your content in a machine-readable way. It enables rich results and helps search engines and AI systems understand entities. It must reflect what is visible on the page.

Security and mobile

HTTPS everywhere, no mixed content, and a responsive design that works on phones — Google indexes the mobile version of your site first.

International and multi-language (where relevant)

Hreflang tags, correct URL structures and consistent targeting so the right version of a page appears in the right country.

Common technical SEO problems we find in audits

• Important pages blocked by robots.txt or noindex left over from development
• Hundreds of thin or duplicate URLs indexed (filters, tags, parameters)
• Redirect chains and loops after migrations
• Core Web Vitals failing on mobile because of unoptimised images and heavy page builders
• Missing or inconsistent canonical tags
• Content loaded only by JavaScript, invisible to crawlers
• Broken internal links and orphaned pages
• Schema that doesn’t match the visible content

How to check your own technical SEO

1. Open Google Search Console → Pages: compare “indexed” to “not indexed” and read the reasons.
2. Run PageSpeed Insights on your home page and a key template; look at the field (real-user) data, not just the lab score.
3. Crawl your site with a tool such as Screaming Frog; look for 4xx/5xx errors, redirect chains, duplicate titles and missing canonicals.
4. Search Google for site:yourdomain.com and scan for pages you don’t recognise.
5. Test a key page with Google’s Rich Results Test for structured-data errors.

When to get professional help

A small brochure site can usually be kept technically healthy with a good host, a lightweight theme and an SEO plugin. Ecommerce sites, JavaScript-heavy applications, large publishers and any site about to migrate are where specialist technical SEO services pay for themselves — the mistakes are expensive and often invisible until traffic drops.

Frequently asked questions

Not sure what’s under the bonnet of your website? Our technical SEO audit gives you a prioritised fix list — request one here.