iperf is the simplest and most effective multiplatform network bandwidth diagnostics software. The tool does not require installation and is launched directly from the command line. It operates on the basis of client-server architecture, i.e.

it is required to run the program instance on both systems, between which we want to measure bandwidth. iperf allows you to measure TCP and UDP band, allows you to freely control many transmission parameters (including TCP window size, MSS, Sudden algorithm), as well as supports multicast and IPv6 transmissions. It is also possible to set a constant transmission speed during the test, perform symmetric tests and many, many more.

The latest version for Windows was compiled by Olivier S. Masse based on Cygwin libraries. For iperf, it requires the presence of the DLL library supplied with the executable file in the directory.