Scapy - Scapy is a powerful interactive packet manipulation program.
benchmark.js - A benchmarking library that supports high-resolution timers & returns statistically significant results.
Winsock Packet Editor - WPE Pro is a packet editor.
PPerf - PowerShell Iperf GUI - A PowerShell script to start iperf and show the output (similar to Jperf).
Nipper - Nipper - Neat Internet Protocol Packet EditoR - is a graphical packet generation tool.
JSBench.me - Javascript performance benchmark playground based on Benchmark.js.