Nginx (pronounced ‘engine x’) is an HTTP and reverse proxy server. It is well known for its high performance and stability. It is pretty feature rich and very simple to configure. Nginx hosts nearly 12.18% (22.2M) of active sites across all domains. Nginx uses event-driven architecture to handle requests. When compared to a thread-per-request model, event-driven is highly scalable with a low and predicatble memory footprint.
Nginx is very easy to setup as a load balancer for an Apache Tomcat farm.