What are the SEO implications of CSR vs SSR?

CSR SEO concerns:

• Googlebot does render JavaScript but via a second wave deferred by days or weeks — content may not be indexed promptly.
• Other crawlers (Bing, social previews, Slack unfurls) do not execute JavaScript — they see an empty shell.
• Meta tags for OG / Twitter cards are missing on CSR pages without SSR or a pre-rendering service.

SSR / SSG advantages:

• Full HTML is available on first byte — crawlers index it immediately.
• Title, description, canonical, structured data are all present in the initial response.
• Faster TTFB and FCP improve Google's page experience signals (LCP, CLS).

Mitigation options for CSR:

• Use a pre-rendering service (Prerender.io) for non-Google crawlers.
• Dynamic rendering — detect crawler user-agents and serve SSR HTML.
• Migrate high-priority landing pages to SSR or SSG.