TECHNICAL · SEO GLOSSARY
SSR vs SSG (SEO)
The choice between server-side rendering (generating HTML per request at the server) and static site generation (pre-building HTML at deploy time) — both produce SEO-safe server-rendered HTML, but with different trade-offs in content freshness, performance, and infrastructure cost.
Definition
SSR (Server-Side Rendering) and SSG (Static Site Generation) are the two primary rendering strategies that produce SEO-safe, server-rendered HTML for web pages. Both deliver complete HTML to Googlebot on the first request without requiring JavaScript rendering — making them preferable to client-side rendering (CSR) for SEO. SSR: HTML is generated dynamically on each request. Content is always current at the moment of request. Latency depends on server processing time. Suitable for: personalised pages, real-time data, frequently updating content. SSR SEO considerations: high server load at scale, potential latency affecting LCP, requires caching strategies to maintain performance. SSG: HTML is pre-built at deploy time. Content reflects the state of the CMS at the time of the last build. Response time is fast (served from CDN cache). Suitable for: content that changes on a controlled schedule (blog posts, documentation, marketing pages). SSG SEO considerations: stale content until rebuild, very large sites may have long build times, real-time content not feasible. The hybrid approaches: ISR (stale-while-revalidate: SSG with timed regeneration), "on-demand ISR" (invalidate specific pages from a CMS webhook on content change), and "partial hydration" (SSG with selective SSR for dynamic components). Most modern content sites use SSG or ISR for most pages (blog posts, product pages, category pages) and SSR only for pages requiring real-time data (search results, user-specific content).
Why it matters for SEO
Choosing between SSR and SSG is the most impactful technical architecture decision for headless CMS SEO. SSG provides the best LCP performance and most reliable first-wave Googlebot crawl experience; SSR is required when content must be current on every request. Choosing CSR (client-side rendering) instead of SSR or SSG for primary SEO content is the most common headless CMS SEO mistake — it results in delayed indexing, poor LCP, and unreliable structured data processing.
How DeepSEOAnalysis checks this
DeepSEOAnalysis detects rendering strategy from the audit response: if the initial HTML contains complete content and structured data, it is consistent with SSR or SSG; if the initial HTML is a near-empty shell with content loaded after JavaScript execution (detectable by comparing initial HTML to rendered content), it indicates CSR. The structured data field in the audit result shows whether JSON-LD was present in the initial HTML response.
GLOSSARY
Related terms
technical
Rendering Mode (SEO)
The method by which a web page\'s HTML is generated and delivered to users and search engines — including server-side rendering (SSR), static site generation (SSG), incremental static regeneration (ISR), and client-side rendering (CSR) — with different implications for SEO performance, content freshness, and indexing reliability.
Read definition →technical
Incremental Static Regeneration (ISR) SEO
A Next.js rendering strategy that serves statically pre-generated pages (fast, SEO-safe) while automatically regenerating stale pages in the background at defined intervals — enabling large content sites to combine SSG performance with acceptable content freshness without full rebuilds.
Read definition →technical
Static Site SEO
The SEO strategy for sites built with static site generators (Gatsby, Astro, Hugo, Eleventy, Next.js SSG mode) — where HTML is pre-built at deploy time and served directly from a CDN without server-side computation, producing excellent Core Web Vitals and reliable Googlebot crawl experiences.
Read definition →technical
Decoupled SEO
The full set of SEO considerations specific to decoupled (headless) web architectures — where content management and content presentation are separate systems — including rendering strategy, structured data implementation in the frontend layer, canonical management, and AI crawler access.
Read definition →technical
Composable CMS
A content management architecture that assembles functionality from multiple specialised best-of-breed services (headless CMS for content, commerce engine for products, search service for discovery) rather than relying on a single monolithic platform — creating flexible but SEO-complex multi-system architectures.
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