iPerf2

iPerf2 is a network performance measurement tool for assessing throughput, latency, link capacity, and responsiveness. A test needs a server to receive traffic and a client to generate and send it. It can measure TCP and UDP traffic in unidirectional, bidirectional, full-duplex, and simultaneous multi-stream configurations. Available measurements include one-way delay, round-trip time, jitter, packet loss, and throughput. The tool supports IPv4 and IPv6, plus multicast including source-specific multicast joins. Reports can include enhanced metrics and can be written in CSV format. The project manual describes an Android client with live meters for throughput, latency, and congestion signals. iPerf2 is available on Android, Linux, macOS, and Windows, and can be self-hosted. The free Community edition covers TCP and UDP testing, throughput and latency metrics, multicast, and IPv4/IPv6. The free Professional edition adds compile-time features including permit-key access gating, server-side latency histograms, and UDP L4S support. The manual describes timestamped HMAC-SHA256 authentication with a configurable replay window. Measurements occur at socket-level reads and writes, so they do not include lower-level protocol-header overhead. iPerf2 and iPerf3 are independent implementations and do not interoperate.

iPerf2 offers multiple traffic patterns and measurements for network performance checks, with free Community and Professional editions. Keep its socket-level measurement scope and lack of iPerf3 interoperability in mind.

It suits network operators and developers who need active TCP or UDP measurements across IP networks. The client-server setup is relevant for users able to run a traffic receiver and a traffic generator.

iPerf2 is a self-hosted tool for generating network traffic and measuring how links respond. It suits network operators and developers who need configurable TCP or UDP checks across IPv4, IPv6, and multicast. Its broad measurement options are useful for controlled diagnostics, but socket-level reporting and incompatibility with iPerf3 narrow its fit.

Overview

Each test needs a server to receive traffic and a client to generate and send it, so iPerf2 is best for environments where you can run both ends of a test. It measures throughput, latency, link capacity, and responsiveness through active traffic rather than passive observation. That setup gives teams control over traffic direction and streams, though it is less suited to readers seeking a ready-made view of network conditions without managing endpoints.

Key features

TCP and UDP tests can run in one direction, both directions, full duplex, or across simultaneous streams. This flexibility helps isolate how a link behaves under different traffic patterns; it also means results depend on choosing a test arrangement that matches the question being investigated.

Measurements include one-way delay, round-trip time, jitter, packet loss, and throughput. Tests also support multicast, including source-specific multicast joins, and both IPv4 and IPv6. Reports can include enhanced metrics and use CSV output, which is useful for retaining results or working with them elsewhere.

The Android client offers live meters for throughput, latency, and congestion signals, extending client-side checks to Android devices. iPerf2 also offers permit-key HMAC authentication: a timestamped HMAC-SHA256 value, with replay limited by a configurable time window. Professional features add server access gating and remotely enabled server-side latency histograms; the Professional source can be inspected and built.

A central constraint is measurement scope: iPerf2 reads and writes at the socket level, without including lower-level protocol-header overhead. Treat its figures as socket-level measurements, not a complete accounting of traffic on the wire. iPerf2 is also an independent implementation from iPerf3, and the two do not interoperate, so it is a poor choice when a test must connect to an iPerf3 endpoint.

Pricing

Both editions cost nothing. Community edition includes TCP and UDP testing, throughput and latency metrics, multicast, and IPv4/IPv6 support. It covers the core testing needs without the Professional feature set.

Professional edition also costs nothing and adds permit-key access gating, server-side latency histograms, UDP L4S support, and compile-time features. It fits teams that need those server controls or measurements; Community gives up those additions. The edition descriptions specify no seat limits, quotas, or trial terms. The project provides ticket and discussion pages on SourceForge for support.

Platforms

iPerf2 supports Android, Linux, macOS, and Windows, with self-hosted deployment. The server-and-client test model makes it particularly relevant to teams able to run test endpoints on their own systems.

Who it's for

Choose iPerf2 for controlled network diagnostics that need multiple traffic patterns, UDP measurements, multicast, or IPv4 and IPv6 coverage. It is a practical fit for operators and developers who can arrange both a receiving server and a traffic-generating client. Look elsewhere if you need iPerf3 interoperability or measurements that include protocol-header overhead.

Pros and cons

• Pros: TCP and UDP tests support multiple directions and simultaneous streams, letting teams examine varied traffic patterns.
• Pros: Delay, jitter, packet loss, throughput, multicast, and IPv4/IPv6 support cover a wide range of active checks.
• Pros: CSV reporting and a live-meter Android client make results usable across desktop and mobile workflows.
• Cons: Tests require a server and client, so iPerf2 needs endpoints under the user's control.
• Cons: Socket-level measurements omit lower-level protocol-header overhead, which limits what the reported figures represent.
• Cons: It cannot interoperate with iPerf3, ruling it out for mixed-version test setups.

Alternatives

LibreSpeed is a free, self-hosted option across desktop, mobile, and web platforms; choose it when a free-and-open-source speed test is the closer match. OpenSpeedTest is a free, open-source HTML5 network speed test with a free embed widget for personal and commercial use, making it a better fit when an embeddable speed test is the priority.

PingPlotter has a free plan limited to one connection, no remote collection, and 10-minute monitoring history, alongside a $29 a month Professional Edition; choose it when those monitoring terms fit your needs. M-Lab NDT is a free option whose hosted tests are open source and maintained by researchers, for readers seeking that hosted-test approach.

Tessabyte offers a 1-user license for $39, paid once, covering Windows and macOS with installation on up to three personal machines; consider it if that license model suits your setup. Cisco ThousandEyes is a paid alternative. Mininet is free and open source, but requires the Linux kernel and is limited by one server's CPU and bandwidth. TRex is free and open source as a Linux application, with hardware and NIC requirements.

Browse the Network Testing Software list for more options.

Verdict

iPerf2 is a strong choice for technical users who can run both test endpoints and want flexible TCP/UDP traffic patterns with a broad set of socket-level measurements. Its free editions and protocol coverage make it useful for controlled checks, while its measurement boundary and lack of iPerf3 interoperability are decisive reasons to choose another tool when wire-level accounting or iPerf3 compatibility matters.