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iperf3
What iperf3 is
iperf3 is a free network measurement tool for checking the bandwidth achievable on IP networks. It can run as either a client or a server and measures throughput over TCP, UDP, or SCTP, reporting results that include throughput and loss. Test settings can be adjusted for timing, protocol, and buffers, which lets users shape a measurement around their needs. Results from either side of a test can be emitted as JSON, including line-delimited JSON for real-time parsing. A library version is also available for use in other programs.
The project is released under a three-clause BSD license and is aimed primarily at users of the perfSONAR measurement suite, for which it was first developed as a bandwidth tester. Officially supported systems listed by the project are Ubuntu Linux, FreeBSD, and macOS. Windows is not officially supported; its FAQ recommends iperf2 to Windows users who run into trouble. ESnet provides source distributions and lists third-party packages, but does not distribute binary packages. The project recommends checking source distribution SHA256 checksums before use. iperf3 is not compatible with the original iperf. The project lists the iperf-3.22 release as including security and minor bug fixes.
Who it suits
iperf3 suits perfSONAR users who need to measure TCP, UDP, or SCTP throughput and use results in other programs. It also fits users who can work with source distributions on Ubuntu Linux, FreeBSD, or macOS.
What it does well
- Measures TCP, UDP, and SCTP throughput.
- Includes client and server functionality.
- Emits JSON, including line-delimited JSON output.
- Offers a library for use in other programs.
- Released under a three-clause BSD license.
What to know first
- Windows is not officially supported.
- ESnet does not distribute binary packages.
- It is not backwards compatible with the original iperf.
Limits
The free software is officially supported on Ubuntu Linux, FreeBSD, and macOS; Windows is not officially supported. ESnet does not distribute binary packages, and iperf3 is not backwards compatible with the original iperf.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| iperf3 | Three-clause BSD license · source distributions; ESnet does not distribute binary packages | Free |
As software.es.net lists them, read 2 Oct 2026. The maker's own page has the final word.
Getting started
- Open the iperf3 project website.
- Choose a listed third-party package or obtain a source distribution.
- If using a source distribution, verify its SHA256 checksum as the project recommends.
- Run iperf3 with client or server functionality and configure timing, protocol, or buffer settings as needed.
Verdict
Choose iperf3 if you need configurable IP bandwidth measurements, structured output, or a library for integration into other programs. Look elsewhere if you need official Windows support or compatibility with the original iperf.
Questions
How much does iperf3 cost?
The listed plan is free. The project uses a three-clause BSD license.
Which systems are officially supported?
The project lists Ubuntu Linux, FreeBSD, and macOS. Windows is not officially supported.
Does iperf3 have a free trial?
No. It is listed as free, with no free trial.
What protocols can it measure?
iperf3 measures TCP, UDP, and SCTP throughput and includes client and server functionality.
Can I use its output in software?
Client and server output can be emitted as JSON, including line-delimited JSON. The project also includes a library version for use in other programs.
Is it compatible with the original iperf?
No. iperf3 is not backwards compatible with the original iperf.
Facts from iperf3's own pages
- Compatibility limit
- iperf3 is not backwards compatible with the original iperf. · software.es.net, 2 Oct 2026
- Distribution
- ESnet does not distribute binary packages; the project lists third-party packages and provides source distributions. · software.es.net, 2 Oct 2026
- Founded
- 2010 · software.es.net, 28 Sept 2026
- Integrations
- iperf3 was developed initially as the bandwidth tester for the perfSONAR measurement suite, which the project identifies as its primary user base. · software.es.net, 2 Oct 2026
- Integrity
- The project recommends verifying SHA256 checksums for source distributions before use. · software.es.net, 2 Oct 2026
- Latest release
- The project news page lists iperf-3.22 as released on 2026-09-29, with security and minor bug fixes. · software.es.net, 2 Oct 2026
- Library
- iperf3 includes a library version of its functionality that can be used in other programs. · software.es.net, 2 Oct 2026
- License
- iperf3 is released under a three-clause BSD license. · software.es.net, 2 Oct 2026
- Output
- Client or server output can be emitted as JSON, including line-delimited JSON for real-time parsing. · software.es.net, 2 Oct 2026
- Protocols
- It measures TCP, UDP, or SCTP throughput and includes both client and server functionality. · software.es.net, 2 Oct 2026
- Purpose
- iperf3 measures achievable bandwidth on IP networks and reports throughput, loss, and other test results. · software.es.net, 2 Oct 2026
- Security
- The project directs reports of potential security issues to [email protected]. · software.es.net, 2 Oct 2026
- Support
- The project provides a developer mailing list and GitHub issue tracker for questions and bug reports. · software.es.net, 2 Oct 2026
- Supported platforms
- Ubuntu Linux, FreeBSD, and macOS are the only officially supported platforms listed by the project. · software.es.net, 2 Oct 2026
- Test options
- Users can tune test parameters related to timing, protocols, and buffers. · software.es.net, 2 Oct 2026
- Windows support
- iperf3 is not officially supported on Windows, and the FAQ recommends iperf2 for Windows users having trouble. · software.es.net, 2 Oct 2026
Where iperf3 stands on Freedom251
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