I’ll ask the guys and girls at fecher to comment on load balancers they used with VWG and are not moving to Wisej. Our load balancing tests were done using Amazon ELB. Haven’t tried the new ALB.
One of the most mentioned open source load balancer seems to be HAProxy.
In general, the web server behind the load balancer should be unaware of the load balancer. All wisej needs to work properly is a load balancer that can route the same session back to the same server (they all do) and, if you want to use WebSocket, a load balancer that works with TCP instead of HTTP.
The additional optional load balancing feature that Wisej offer is the ability to return 503 under certain conditions using healthcheck.wx.