Jamstack is a web architecture where pages are pre-rendered at build time and served from a CDN, with dynamic functionality handled by JavaScript calling APIs and serverless functions. The name originally stood for JavaScript, APIs, and Markup. The core idea is decoupling the frontend from the backend, treating the web layer as a static deployment enhanced by services.
How It Works
In a Jamstack architecture, a static site generator (Next.js, Astro, Hugo, Eleventy) compiles your content and templates into HTML files during a build step. These files deploy to a CDN edge network. When dynamic behavior is needed (form submissions, authentication, database queries), client-side JavaScript calls third-party APIs or your own serverless functions.
Content often comes from a headless CMS (Contentful, Sanity, Strapi) via API at build time. Git acts as the deployment trigger: push to main, the CI/CD pipeline builds the site, and the CDN invalidates its cache. The entire site updates in minutes.
Why It Matters
Jamstack sites are fast by default. Pre-rendered HTML on a CDN delivers sub-100ms load times without performance tuning. Security improves because there is no server to attack, no database exposed to the internet, and no runtime code injection vector. Scaling is trivial because CDNs handle traffic spikes that would collapse traditional servers.
Developer experience benefits too. Frontend teams work independently, preview deployments show every pull request, and atomic deploys mean rollbacks are instant.
In Practice
A SaaS marketing site built with Astro pulls content from Sanity CMS, renders pages at build time, and deploys to Vercel's edge network. The pricing page calls a serverless function to fetch current plan details. Contact forms submit to a Resend API endpoint. Analytics run client-side through PostHog. No origin server exists.
Common Mistakes
Jamstack struggles with highly personalized content, real-time data, or sites with thousands of pages that change frequently. Build times grow with page count. The architecture works best for content-driven sites, marketing pages, documentation, and e-commerce catalogs, not for real-time dashboards or collaborative applications.