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Flent vs Ethr: catalog facts
Flent	Ethr
Free Free to download and use, with the source published on GitHub.	Free Free and open source under the MIT licence.
Linux, Command line	Windows, macOS, Linux, Command line
Repeatable aggregate tests built on netperf and iperf Interactive GUI and extensive plotting	Covers TCP, UDP and ICMP in one tool Same tool on Windows, Linux and macOS
Needs netperf or iperf and a test server on the other end Aimed at technical users rather than a quick speed check	Command-line only No formal releases listed on the repository
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: MIT
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.