Wireshark
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Official site of Wireshark, the open-source network protocol analyzer, with downloads, the user's guide, and sample captures. Learners can capture live traffic, filter and decode packets across hundreds of protocols, and trace latency, retransmissions, and other performance problems.
More resources on Network Performance
iperf
Download and documentation site for iPerf and iPerf3, the command-line tool for measuring maximum TCP, UDP, and SCTP throughput between two hosts. Covers client and server options, so learners can run bandwidth tests and interpret jitter and packet loss results.
High Performance Browser Networking
Free online edition of Ilya Grigorik's O'Reilly book on the networking layers beneath web applications. Covers latency, TCP and UDP behavior, TLS, wireless and mobile networks, HTTP/1.x, HTTP/2, WebSocket, and WebRTC, explaining how each affects page load performance.
The Bits and Bytes of Computer Networking
Introductory course from Google's IT Support certificate on how computer networks work, covering the five-layer TCP/IP model, Ethernet, IP addressing and subnetting, TCP and UDP, DNS and DHCP, NAT, and troubleshooting tools. Learners can explain and diagnose everyday network connectivity problems.
web.dev
web.dev is Google's developer resource hub with guides, tutorials, and tooling docs to help you build fast, accessible, and reliable websites. It covers web performance topics like Core Web Vitals, Lighthouse audits, performance best practices, and network optimization techniques.