Technical SEO: the foundation every other part of search depends on

What technical SEO covers, and what it does not

A page can only appear in search results after a search engine has found it, fetched it, processed it and decided it deserves a place in the index. Google describes this as crawling, indexing and serving results in its explanation of how Google Search works. Technical SEO is everything that keeps those steps running cleanly.

It helps to separate three questions. Content decides whether your page is the strongest answer. Authority decides whether others vouch for you. Technical SEO decides whether a search engine can read the page properly at all. Fixing the third question will not rescue a weak page. But a stray noindex tag, a migration without redirects or a menu that crawlers cannot follow can make months of good work invisible.

That is why a technical SEO agency should be judged on prioritisation as much as knowledge. Most sites have dozens of technical imperfections. Only a handful actually limit performance, and the job is to find those first.

Crawling: can search engines reach your pages?

Crawling is discovery. Googlebot follows links and reads XML sitemaps; anything it cannot reach does not exist as far as search is concerned.

What we check

• robots.txt. Does it block pages, scripts or stylesheets that matter? Note that robots.txt controls crawling, not indexing. To keep a page out of results you use a noindex directive, as Google explains in its guidance on blocking indexing.
• XML sitemaps. Do they list only indexable URLs that return a 200 status, and are they submitted in Search Console?
• Status codes. Error pages, server errors and redirect hops that waste crawl effort.
• Crawl traps. Filters, sort orders, calendars, internal search and URL parameters that generate endless variants of the same page.

Crawlers, crawl budget and log files

To see your site as a search engine does, run a crawler such as Screaming Frog SEO Spider or Sitebulb, which records each URL's status, canonical, title, internal links and click depth. Set the result beside the page indexing report in Search Console: the gap between what you want indexed and what Google actually indexes is usually more revealing than any tool score.

Crawl budget is the attention Google gives your site. Google's documentation on managing crawl budget makes clear it mainly concerns very large or fast-changing sites. For those, server log analysis shows which URLs Googlebot really requests, how often, and where crawling is wasted on pages that do not matter.

Rendering: JavaScript and what Google actually sees

Many modern sites assemble their content in the browser with JavaScript. Google can render JavaScript, but does so as a separate step and not always perfectly. Its JavaScript SEO basics set out the main risks.

• Key content in the initial HTML. Text and links that appear only after a click, a scroll or a delayed API call may be missed.
• Real links. Navigation should use ordinary anchor elements with an href. Buttons that change the page through a script cannot be followed.
• Server-side rendering or static output for pages that need to rank: faster for visitors and more dependable for crawlers.
• Verification. The URL Inspection tool in Search Console shows the rendered HTML Google works with, which settles most arguments between marketing and development.

Indexing: duplicates, canonicals and noindex

Not every URL belongs in Google. A healthy index holds your valuable pages, each on one stable address, and very little noise.

• Duplicate URLs. The same page reachable with and without www, over http and https, with and without a trailing slash, or with tracking parameters. Choose one version and redirect the rest.
• Canonical tags. A canonical tells Google which version you prefer. It is a strong hint rather than a command, as Google explains in consolidating duplicate URLs.
• Noindex. For pages that must exist but should not appear in results, such as internal search results or thank-you pages after a form.
• Thin and outdated pages. Tag archives, empty categories and expired offers that dilute the overall quality of the site.
• Faceted navigation on shops. Filter combinations can create thousands of near-identical URLs. Decide which filters deserve an indexable page because people genuinely search for them, and keep the rest out. Our ecommerce SEO work deals with this in depth.

Site architecture and internal links

The structure of a site tells search engines what matters and how topics relate. It also helps visitors find what they came for.

• Shallow click depth. Important pages sit a few clicks from the home page.
• Clear clusters. A hub page per topic links to its detailed pages, and they link back.
• No orphan pages. Pages without internal links are found late and carry little weight.
• Descriptive anchor text. "Read about local SEO for clinics" tells a crawler far more than "click here".
• Readable URLs and breadcrumbs that reflect where a page sits in the structure.

The aim is clarity, not perfection: every important search has one strong page, and your internal links make it obvious which one that is.

Redirects, migrations and international sites

Redirects and status codes

A 301 is a permanent redirect and passes signals to the new address; a 302 is temporary. Chains of redirects slow crawling and loading. Removed pages with no replacement should return a 404 or 410. Sending every deleted URL to the home page tends to be treated as a soft 404 and helps no one.

Migrations

A new website, CMS, platform or domain is when technical mistakes cost the most. Every old URL with traffic, rankings or links needs a matching destination before launch. Our website migration service covers the full process, from inventory to post-launch monitoring.

Hreflang for multilingual and multi-country sites

If you run versions for different languages or countries, for example a UK site alongside Irish, German or US versions, hreflang tells search engines which version suits which user. Each version must reference itself and every alternative, and the references must be reciprocal. Google sets out the rules in its guide to localised versions of your page. The strategic choices around it, such as domain structure and localisation, sit under international SEO.

Core Web Vitals, speed and mobile

Core Web Vitals are three measures Google uses to describe the experience of a page. Google's Core Web Vitals documentation gives these thresholds for a good experience:

• Largest Contentful Paint (LCP): the main content loads within 2.5 seconds.
• Interaction to Next Paint (INP): the page responds to a tap or click within 200 milliseconds.
• Cumulative Layout Shift (CLS): the layout stays stable, with a score of 0.1 or less.

Google assesses these at the 75th percentile of real visits, separately for mobile and desktop. Field data from real users therefore matters more than a single lab test in PageSpeed Insights. Core Web Vitals are one signal among many: a fast page with a weak answer will not beat a slightly slower page with a strong one. Slow, jumpy pages do, however, lose visitors and enquiries.

Mobile matters just as much. Google primarily uses the mobile version of a page for indexing, so content, links and structured data that exist only on desktop may as well not exist.

Structured data and technical SEO for AI search

Structured data is code, usually JSON-LD using the schema.org vocabulary, that states what a page contains: an organisation, a product, an article, a breadcrumb trail. It can make a page eligible for richer results, although Google decides whether to show them. See Google's introduction to structured data.

• Markup must match what is visible. Reviews, prices or questions that do not appear on the page do not belong in the code.
• A few correct types beat a pile of markup that contradicts the page.
• Test with the Rich Results Test and monitor the enhancement reports in Search Console.

Technical SEO for AI search follows the same logic. AI assistants and Google's AI features draw on pages that can be fetched, rendered and parsed reliably. Clean HTML, consistent entity information and pages that answer questions directly make your content easier to understand and cite. The wider approach is covered under AI SEO.

A technical SEO checklist and the tools to use

Use this as the starting point for a technical review. Not every row weighs the same for every site: an online shop with tens of thousands of URLs carries different risks from a professional services firm with forty pages. Start with whatever touches your most important pages, and work from blockers to refinements.

Working with a technical SEO agency

Technical SEO is a collaboration. A specialist diagnoses what is wrong and what fixing it is worth; your developer or platform partner usually implements it. Things go wrong when the two work past each other, or when a list of a hundred findings arrives without an order.

Our technical work therefore starts with an analysis of the whole site. In our SEO audit, technical foundation and indexing is the first of ten fixed points, alongside speed and Core Web Vitals, keyword and content coverage and the rest. You then receive a prioritised plan written as tickets your own developers can pick up, or that we carry out within a fixed scope. On sectors with extra sensitivities, such as law firm SEO, we also check that trust and compliance information is crawlable and consistent.

What drives the effort: the number of URLs, the platform and how much control it allows, JavaScript dependence, the number of languages and countries, the state of past migrations and whether you want implementation or advice only.

Every engagement starts with the paid Beacon Strategy Session: 50 minutes with the founder for £225 excluding VAT. It is a conversation about your ambition, your market and fit, not a technical review. Afterwards we decide whether to take the project on; if we do, a proposal with a fixed scope and fixed price follows.