Term
Server-side rendering
An approach in which the server sends the browser finished HTML instead of an empty shell that JavaScript fills in. The page appears faster, and search engines and AI crawlers see all the content straight away.
Updated
What it means
Server-side rendering, or SSR, is an approach in which the server sends the browser the finished HTML of a page. The browser can display it straight away, and JavaScript loads afterwards to add interactive parts such as forms or filters.
The opposite is client-side rendering, where the server sends only an empty shell and content appears once JavaScript has downloaded and run. Such a site can feel slow, especially on weaker phones, and some search engine or AI crawlers may not see the content at all.
A related approach is generating pages in advance at build time, which produces a static website. While SSR builds HTML on every request, static generation prepares it once and the server merely sends the files, which is even faster and cheaper to run.
How it works in practice
For company websites, blogs and glossaries, SSR or static generation matters for technical SEO. The search engine receives all the text, headings and links in the very first response and does not have to wait for scripts to run, which makes indexing simpler.
Ready HTML also helps with Core Web Vitals metrics, especially how fast the main content appears. Users see text sooner and the page shifts less, which improves the impression of the site and its position in search results.
SSR is growing in importance for generative engine optimisation. Language models and their crawlers often do not execute JavaScript, so content that exists only after rendering in the browser may never make it into their answers and citations.
What to watch out for
SSR puts more load on the server, since it must assemble the page on every visit. For a site whose content changes rarely, static generation or a combination with caching is often better, reducing both load and hosting costs.
When moving to a new website, for example with a headless CMS, it is worth checking that important content really is present in the HTML. A simple test is to view the page source and search for the text, or to use the search engine's rendering inspection tools.
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