Iperf3 outputs JSON incrementally only at the end of a test when using the default interval. To achieve real-time updates, we use the -i 1 flag (interval 1 second) and parse the "intervals" array from the stream:
—Network performance testing is critical for infrastructure validation. Iperf3 is the industry standard for measuring maximum TCP/UDP throughput, but it lacks a native, modern graphical user interface (GUI) on Windows platforms. This paper presents Iperf3-Cygwin-GUI , a wrapper application that leverages the Cygwin POSIX emulation layer to execute Iperf3 on Windows while providing a real-time, interactive dashboard. We discuss the architectural challenges of bridging a Windows GUI (C#/WPF) with a Cygwin-based process, the implementation of real-time stream parsing, and performance benchmarks comparing the GUI overhead against native CLI execution. Results show that the GUI introduces less than 2% CPU overhead and no measurable impact on throughput accuracy. Iperf3-Cygwin-GUI
| Tool | Avg. Throughput (Mbps) | Std Dev | Retransmits | |------|------------------------|---------|--------------| | iperf3-win (CLI) | 941.2 | 2.1 | 12 | | Iperf3-Cygwin-GUI | 940.8 | 2.3 | 13 | Iperf3 outputs JSON incrementally only at the end
Using Windows Performance Monitor during a 60-second test: | Tool | Avg