Simulating TCP Loss and Congestion in Browser Using Go/WASM

I built ccsim to run full gVisor netstacks in WebAssembly, allowing you to simulate TCP congestion directly in your browser. You can compare stock Cubic against a custom BBRv3 implementation while visualizing real-time loss, jitter, and throughput. The tool reveals how aggressive senders cause congestion collapse, filling queues with retransmissions while actual goodput plummets despite high link utilization.