SSR vs CSR vs SPA: What Most Developers Get WRONG

If you’ve worked with React, PHP, Django, Symfony, or modern SaaS products, you’ve probably heard terms like SSR, CSR, and SPA. They’re everywhere in web development, yet many developers use them without fully understanding the trade-offs behind each approach. In this article, I break down the differences between Server-Side Rendering (SSR), Client-Side Rendering (CSR), and Single-Page Applications (SPA) using practical examples from real-world software engineering. You will see how traditional server-rendered applications work, why frameworks such as Symfony, Rails, and Django have relied on SSR through Smarty, Twig, ERB, and Jinja2 for years, why SSR applications are (often) easier and simpler to build than CSR, and how modern frontend frameworks like React changed the way we build applications by moving much of the rendering logic to the browser. You’ll also learn why client-side rendering creates a clear separation between frontend and backend systems, what performance implications come with that choice, and when a single-page application can provide a smoother user experience for products such as dashboards, internal tools, and SaaS platforms. Whether you’re preparing for software engineering interviews, learning web architecture, or simply trying to better understand the technologies you use every day, this article provides a straightforward explanation of these core concepts without unnecessary complexity. By the end, you’ll understand: • What SSR, CSR, and SPA actually mean. • How data flows in each architecture. • The advantages and disadvantages of every approach • When to choose one over another. • Why modern applications often combine multiple rendering strategies. These concepts sit at the foundation of modern web development, and understanding them will help you make better architectural decisions for your next project. This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit www.pierrehenry.dev