Frontend and backend are often treated as opposite worlds, each with its own tools, constraints, and claims about which side is harder. But are they really so different?Modern frontend applications increasingly resemble distributed systems. Multiple tabs drift out of sync. Shared caches require invalidation. Optimistic updates collide with server state. Requests fail, retries duplicate work, and yesterday’s truth becomes today’s stale data. What looks like everyday UI code quickly becomes a coordination problem.Backend engineers will recognize these challenges immediately: establishing a single source of truth, defining data ownership, validating untrusted input and observing systems in production.In this talk, we’ll cross the frontend-backend divide and explore the shared principles behind these problems. We’ll see what frontend development can learn from backend thinking, what the backend can learn from reactive interfaces, and in the end a glimpse on how Effect provides practical patterns for building resilient, observable, and maintainable applications on both sides of the stack.
