xfr

xfr is a terminal network throughput testing tool, built to measure bandwidth between hosts and report results in real time during a run.

It runs TCP, UDP and QUIC, and also tunes bitrate, duration, interval, and parallel streams. The server handles multiple clients at once, and keeps TCP on only a single port. It supports reverse and bidirectional tests, firewalls, outputs to plain text, JSON, JSON streaming or CSV, and also can compare past runs. 

This tool also has a LAN discovery feature to find local servers, plus optional Prometheus metrics, themes, keyboard bindings and update notifications as a way to prompt you to update the program when needed.

For network engineers, SREs or those who need to diagnose slow paths or compare transports, xfr is useful for network heavy use cases, such as testing data center networks, VPN testing and network benchmarking where repeatable bandwidth numbers matter.