Refract Group2026
Glossary
Technical SEO
Technical SEO is the part of search engine optimisation that makes sure search engines can crawl, render and index a site’s pages, each at one address, and that the pages load fast enough for the people who arrive.
- URL discoveredFrom a link or the sitemap
- Allowed to fetch?Never crawled
- RenderedScripts run, final HTML read
- IndexedOne canonical URL kept
- Shown in resultsRanked against other pages
Technical SEO in detail
- Also called
- Technical search optimisation, Crawlability, Indexability, Site health
- Updated
What it is
Technical SEO is the machinery under the content. Google handles a page in three phases: it crawls the URL, renders the page by running its JavaScript, then indexes what it found. Each phase can fail while the page looks fine in a browser. A technical review checks these, template by template:
- Access: robots.txt, CDN and firewall rules, and noindex tags that keep pages out.
- Addresses: one canonical URL for each page, permanent redirects from old ones, and a sitemap that lists only the canonical form.
- Rendering: whether the copy is in the HTML the server sends, or appears only after scripts run.
- Speed: the Core Web Vitals, where good means LCP within 2.5 seconds, INP within 200 milliseconds and CLS at most 0.1, at the 75th percentile of visits.
- Structured data that describes what is on the page.
Why it matters
A page that is never indexed does not exist as far as search is concerned, and technical faults tend to hit whole sections at once: one template with a noindex tag, one rule that sends every old address to the homepage. The audience has also grown. Google says server-side rendering or pre-rendering is still a good idea because not all bots run JavaScript, and the crawlers behind AI search are now among the readers a company wants.
How we do it
Our sitemap lists every public page in the canonical form the pages declare: lowercase, no trailing slash, no query. A page gets a lastmod date only where the site records a real change, such as an article’s updated date, and never the build date, which would claim a change that did not happen.
We found /about/ answering with the same page as /about, two addresses for one page, so every trailing-slash address now redirects permanently to the bare one. Old case-study addresses that Search Console listed as not found each redirect with a 301 to the current page with the same content, written out one by one with no catch-all rule. Retired projects with no replacement still return not found.
An example
Say a developer tools company builds its pricing page as a single-page app, with the plans fetched from an API after the page loads. In a browser it looks complete. Viewing the source shows an empty container. Google can render it after a wait in its render queue, but a crawler that does not run JavaScript reads a page with no prices on it. The fix is to render the plans on the server, so every crawler gets them in the first response.
Common mistakes
- Sending every old URL to the homepage. A redirect should lead to the page with the same content, and where there is none, an honest not found serves the visitor better than an unrelated page.
- Stamping every page with the build date. Google uses a sitemap’s lastmod only when it is consistently and verifiably accurate, so a date that changes on every deploy teaches it to ignore yours.
- Blocking the crawler you wanted. A CDN bot rule or a robots.txt line written for one crawler can shut out others, so check each crawler you care about against both.
- Using a temporary redirect for a permanent move. Google reads a 301 or 308 as a sign that the new address should be the canonical one, and a 302 or 307 does not carry that signal.
Technical SEO vs on-page SEO
Technical SEO decides whether search engines can reach, render and index a page, and on-page SEO decides what the page tells them and the reader once they do.
| Technical SEO | On-page SEO | |
|---|---|---|
| Works on | Servers, templates and site settings | Titles, headings, copy and links |
| Done by | Developers and whoever runs hosting | Writers, marketers and designers |
| Reach | Whole sections at once | One page at a time |
| Checked with | Crawl reports and server responses | The page read against the search |
Questions
What people ask about technical SEO.
Technical SEO covers crawl access through robots.txt and the CDN, indexing and noindex tags, canonical URLs, redirects, XML sitemaps, whether JavaScript content renders, structured data and page speed measured by the Core Web Vitals. What the copy says belongs to on-page SEO.
Google’s Core Web Vitals count a page as good when Largest Contentful Paint is 2.5 seconds or less, Interaction to Next Paint is 200 milliseconds or less and Cumulative Layout Shift is 0.1 or less. Each is measured at the 75th percentile of real visits, on phones and desktops separately. INP replaced First Input Delay in 2024.
An XML sitemap should list the canonical URL of every page you want in search, up to 50,000 URLs or 50MB a file, with a lastmod date where you know when the page last changed in substance. Google ignores priority and changefreq. A sitemap Search Console accepts has been read; whether each page is indexed is a separate check.
Where this shows up in our work
Related terms
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