Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Web ScrapBook - A browser extension that captures the web page faithfully with highly customizable configurations.
tcpdump - tcpdump is a common packet analyzer that runs under the command line.
Offline Pages Pro - Offline Pages Pro is probably the world’s most advanced offline browser.
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
wpull - Wpull is a wget-compatible web downloader and crawler with WARC and Python/Lua scripting support