Technical SEO
What is technical SEO?
Technical SEO is everything that determines whether a search engine can crawl a site, render it, index it and correctly read its structure. On its own it does not make a page relevant to a query, and it does not build authority. What it does is remove the obstacles that stop good content and strong links from turning into visibility, which is why a technical diagnosis usually comes first in SEO work.
| Layer | Question it answers | Examples |
|---|---|---|
| Technical SEO | Can Google find, render and index the page? | robots.txt, canonical tags, redirects, JavaScript rendering |
| On-page SEO | Does the page answer the query? | content, headings, title tag, in-text links |
| Off-page SEO | Do other sites treat it as credible? | backlinks, brand mentions |
What technical SEO covers
- Crawling — robots.txt, internal linking and the XML sitemap. Crawl budget matters mainly on very large sites or sites whose content changes very often; on a typical company website it is rarely the bottleneck.
- Rendering — whether the content is in the HTML right away (server-side rendering or static generation) or appears only after JavaScript runs in the browser. In the second case Google has to render the page first, and that step can be delayed. The JavaScript SEO entry goes into detail.
- Indexing — noindex directives, canonical URLs, duplicate content, index bloat, status codes (404, 410, soft 404), 301 redirects and redirect chains.
- URL architecture — readable URLs, click depth, and how pagination and filters are handled.
- Supporting signals — structured data, hreflang for language versions, HTTPS and mobile-first indexing.
- Core Web Vitals — LCP (loading), INP (responsiveness to interaction) and CLS (layout stability). INP replaced FID as a Core Web Vital on March 12, 2024. Google considers LCP up to 2.5 s, INP up to 200 ms and CLS up to 0.1 as "good", measured at the 75th percentile of visits.
How technical SEO is measured
- Google Search Console — the "Pages" report under Indexing (what is indexed and why the rest is not), "Crawl stats" in Settings, the "Core Web Vitals" report built on field data from the Chrome UX Report (CrUX), and the URL Inspection tool for individual pages.
- A crawler such as Screaming Frog or Sitebulb, which replays a bot's path through the site: status codes, canonicals, redirects, depth, pages with no internal links pointing to them.
- Log file analysis, which shows what Googlebot actually fetches rather than what it could fetch.
- The Rich Results Test, which validates structured data.
One distinction matters more than any tool. Lighthouse simulates a single page load under lab conditions, while Google assesses page experience on field data collected from real Chrome users. Core Web Vitals status is therefore decided by CrUX, not by a Lighthouse score.
What does a technical SEO consultation deliver?
A technical consultation or audit should hand the team a concrete work list, not a report that ends up in a drawer:
- An inventory of problems — what blocks crawling, rendering and indexing, on which URLs, and at what scale.
- Priorities — each issue weighed by its impact on visibility against the cost of fixing it.
- Specifications for developers — each change described precisely enough to be implemented and tested.
- Verification after release — a fresh crawl and a check in Search Console that the fix actually worked.
That is the scope of an SEO audit, and the step-by-step process is laid out in how to conduct an SEO audit. Some of these checks can be automated: on this site, the build stops when an internal link points to a page that does not exist or passes through a redirect.
Common mistakes
- A Disallow rule in robots.txt on a URL that also carries noindex. The bot never fetches the page, so it never sees the noindex, and the URL can still end up in the index without its content.
- A canonical pointing to a URL that redirects, returns 404 or is set to noindex.
- An XML sitemap listing non-canonical, redirected or blocked URLs.
- Redirect chains instead of a single hop to the final URL.
- Blocking JavaScript and CSS files in robots.txt that the page needs in order to render.
- Treating a Lighthouse score as a goal in itself.
Related terms
- Crawlability — whether a bot can reach the page at all, the first condition of visibility
- Indexing — the stage where Google decides whether a page enters its results
- Canonical URL — the preferred version among duplicates
- Core Web Vitals — page experience metrics measured on field data
- Log file analysis — the only record of what the crawler actually visits
- Search Console — Google's own view of how it crawls and indexes a site