iperf3 vs LibreSpeed

iperf3 is a free command-line network measurement tool that reports achievable IP-network bandwidth, throughput, loss, and related results. It includes client and server functions for TCP, UDP, and SCTP tests, with adjustable timing, protocol, and buffer settings. Client or server output can be emitted as JSON, including line-delimited JSON for real-time parsing, and a library version can be embedded in other programs. The project uses a three-clause BSD license and lists Ubuntu Linux, FreeBSD, and macOS as its officially supported platforms. Windows is not officially supported; its FAQ points users with Windows problems toward iperf2. ESnet supplies source distributions rather than binary packages and recommends checking SHA256 checksums. iperf3 began as a perfSONAR bandwidth tester, its primary user base. It is not backwards compatible with the original iperf. Version 3.22 was released September 29, 2026.

LibreSpeed is a lightweight JavaScript speed test that uses XMLHttpRequest and Web Workers to measure download, upload, ping, and jitter. It supports IE11, current Edge, Chrome, Firefox, Safari, and mobile browser versions. Telemetry and result sharing are optional, and an installation with multiple test points can automatically select the point with the lowest ping. A separate stability test reports current, average, minimum, and maximum latency, jitter, failed-request percentage, threshold alerts, and CSV export. It can target a local backend, configured test points, or Google, Cloudflare, and Apple. Deployment uses a web server such as Apache, nginx, or IIS with PHP 5.4 or newer, though other backends are available. Optional result storage supports MariaDB, MySQL, Microsoft SQL Server, PostgreSQL, and SQLite. The project provides an Android client template, a command-line client, and a .NET client library through NuGet. Go and Rust implementations are available; the Node.js implementation is partial and not recommended. LibreSpeed is free and open source, with self-hosting and no paid plans listed.