APISIX

APISIX is an API gateway built on Nginx and Lua that sits in front of your microservices, handling routing, authentication, rate limiting, and payload transformation fast enough for serious traffic. It routes API calls to the right backend service and applies policies (auth, rate limits, logging) without changing your application code.

Fully free under Apache 2.0. APISIX is an Apache Software Foundation project with no commercial entity gating features. You get the full gateway: dynamic routing, load balancing, 80+ plugins (auth, observability, traffic control), gRPC support, and a dashboard. Plugins are hot-reloadable, no restarts required.

The catch: the Lua/OpenResty foundation is niche. If your team doesn't know Lua, writing custom plugins is a steep learning curve. Envoy and Traefik have larger communities and more ecosystem integrations. And while APISIX is fast, the operational complexity of running an API gateway at scale (high availability, configuration management, monitoring) is real regardless of which tool you pick.