Every agency has a default stack. Ours is a Next.js front end talking to a FastAPI back end, and we reach for it because it lets a small team move quickly without painting itself into a corner six months later.
The front end: Next.js
Server components and static generation give us SEO-friendly pages out of the box, which matters when a marketing site's entire job is to be found. The same app can host an authenticated dashboard, so the public site and the product share one design system.
The back end: FastAPI
FastAPI gives us typed request and response models, automatic OpenAPI docs, and async I/O that holds up under concurrent load. Pairing it with SQLAlchemy and Alembic keeps the data layer explicit and migrations reviewable.
Why the split is worth it
A clean API boundary means the same back end can serve the website, a mobile app, and a partner integration without rework. That optionality is the whole point.