Edge functions are pieces of server code that run across a global network of locations rather than in one central data centre. Each visitor’s request is handled by the nearest point in that network, which keeps the response time low because the data travels a shorter distance. They are the plural, broader idea behind a single edge function, the general capability of running logic at the edge.
Imagine a national newspaper printed in twenty cities instead of one. Readers get the paper from their local press at dawn, not from a single plant that then ships copies across the country overnight. Edge functions follow the same pattern, running on the same kind of distributed network as a CDN, but executing live code: checking a token, rewriting a URL, or choosing which version of a page to show.
They shine for small, fast decisions that should happen before a request reaches your main system. A common use is checking whether someone is logged in and redirecting them, or splitting traffic between two versions of a page for an A/B test. Heavy processing, large databases and long jobs still belong on a central server.
But there is a catch worth knowing. Edge functions run in a stripped-down environment with tight limits on memory and execution time, and they often can’t reach a database sitting in one region without paying the very latency you were trying to avoid. So the rule of thumb is simple: keep them small, fast and stateless. Anything that needs your full database is better off on the main backend.
At TopDevs we use edge functions to put time-sensitive logic close to users, so a client’s site stays fast for visitors in Amsterdam, New York and Singapore alike.
