Flent vs iPerf2

Flent has no write-up on Specifiction yet; its figures are above.

iPerf2 measures network traffic performance, including throughput, latency, link capacity, and responsiveness. Testing uses a client to send traffic to a server. It can generate TCP and UDP traffic in one-way, bidirectional, full-duplex, and simultaneous multi-stream configurations. Measurements include one-way delay, round-trip time, jitter, packet loss, and throughput. It supports IPv4, IPv6, and multicast, including source-specific multicast joins, and reports can include enhanced metrics or use CSV format. The project manual describes an Android client with live meters for throughput, latency, and congestion signals. The manual also describes permit-key HMAC authentication using a timestamped HMAC-SHA256 value, with replay limited by a configurable time window. Its Professional feature set includes server access gating and remotely enabled server-side latency histograms. Measurements happen at socket-level reads and writes, so lower-level protocol-header overhead is excluded. iPerf2 and iPerf3 are separate implementations and do not interoperate. It runs on Android, Linux, macOS, and Windows, and can be self-hosted. Both listed editions are free.