Vercel Edge Config, Middleware, and Feature Flags: Underused Tools Most Teams Aren't Using Yet

A lot of the Vercel platform's most useful tools solve problems teams have already worked around some other way — a config value baked into an environment variable and redeployed on every change, a feature flag hand-rolled with a database lookup on every request, personalization logic duplicated in every route.

Edge Config gives you a low-latency key-value store you can update without a redeploy. Routing Middleware lets you intercept and rewrite requests before they hit your app's cache. Feature flags built on top of both let you ship code dark and turn it on for a subset of traffic without a deploy at all.

This post covers where each of these actually earns its place in an app versus where they're overkill, based on what's come up in client work.