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Flent vs nuttcp: catalog facts
Flent	nuttcp
Free Free to download and use, with the source published on GitHub.	Free Free and open source.
Linux, Command line	Windows, macOS, Linux, Command line
Repeatable aggregate tests built on netperf and iperf Interactive GUI and extensive plotting	Handles high-throughput TCP and UDP testing beyond typical consumer speed tests Cross-platform command-line tool suited to scripting and automation
Needs netperf or iperf and a test server on the other end Aimed at technical users rather than a quick speed check	Requires installing and running the tool on both ends of the connection Command-line only, with a learning curve for new users
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License not stated
No account needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 22, 2026

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