Technical SEO is the work of making sure search engines and AI can reach your pages, understand them and show them to searchers. This guide goes through the areas of technical SEO in the order in which they are best checked.

What is technical SEO?

Technical SEO is the foundation of search engine optimization. It does not bring visitors on its own, but without it content work can go to waste. If a page is blocked from crawlers or is not indexed, what it says does not matter.

The work comes down to four questions: can the crawler reach the page, is the page stored in the index, does the search engine understand the content, and does the page work quickly for the visitor?

1. Crawling: can the crawler reach the pages?

  • robots.txt tells crawlers where they may go. Check that it does not block important pages or style files.
  • The sitemap (sitemap.xml) lists the pages you want in search. Submit it in Search Console.
  • Internal links are the crawler’s route. An important page needs an ordinary link from another page.
  • Status codes. A working page returns 200, a removed one 404 or 410 and a moved one 301.

2. Indexing: is the page stored?

The Pages report in Search Console shows which pages are indexed and why some are not. The most common causes are a noindex tag, a canonical address pointing to another page and duplicate content.

Decide on one official address for each piece of content. If the same content is available at several addresses, for example because of parameters or filters, use a canonical tag to say which is the right one. Troubleshooting a single page is covered in the indexing guide.

3. Structure: does the search engine understand the site?

  • Addresses are short, readable and permanent.
  • The hierarchy is shallow: the most important pages are a few clicks from the homepage.
  • Headings describe the content: one H1 with a logical H2 and H3 structure beneath it.
  • The title and meta description are unique on every page.
  • Internal linking connects pages on the same subject. See the internal linking guide.

4. Speed and mobile

Google assesses page experience with the Core Web Vitals: how quickly the main content loads, how quickly the page responds and whether the layout stays in place. Measure data from real visitors when it is available rather than staring at a single test result.

Google indexes a site primarily on the basis of its mobile version. The content, links and structured data therefore have to be the same on a phone as on a computer. In more detail: the Core Web Vitals guide.

5. JavaScript and rendering

If a page’s content is only created in the browser with JavaScript, the search engine has to render the page before it sees the content. Google can do that, but it is slower and more error-prone, and not every AI crawler runs JavaScript at all. The safest course is for important content and links to be in the HTML the server sends.

6. Structured data

Schema markup states in machine-readable form what a page is about: an organization, a service, an article, an author or frequently asked questions. The markup has to match what is actually visible on the page.

7. Language versions, security and changes

  • Language versions are connected with hreflang tags, and each language has its own address. See the multilingual SEO guide.
  • HTTPS is in use on every page, and old http addresses redirect to the new ones.
  • Redirects use a 301 straight to the final address, without chains.
  • A redesign is planned so that old addresses are redirected to new ones before launch. See the website migration SEO guide.

Technical SEO checklist

  • The most important pages are indexed.
  • robots.txt does not block important content.
  • The sitemap is up to date and submitted in Search Console.
  • Every page has its own title, one H1 and a canonical address.
  • There are no broken links or redirect chains.
  • Core Web Vitals are in order on mobile.
  • Important content is visible in the HTML without JavaScript.
  • Schema markup passes Google’s test.
  • Language versions are connected with hreflang tags.

If you would like us to go through your website, that is part of technical SEO and the SEO audit. The whole picture is in the search engine optimization (SEO) guide.

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