WebSiteSniffer is described as 'packet sniffer tool that captures all Web site files downloaded by your Web browser while browsing the Internet, and stores them on your hard drive under the folder that you choose' and is an app in the Network & Admin category. There are more than 10 alternatives to WebSiteSniffer for a variety of platforms, including Windows, Mac, Linux, Android and BSD. The best alternative is Wireshark, which is both free and Open Source. Other great apps like WebSiteSniffer are Wget (Free, Open Source), Fiddler (Freemium), WebCopy (Free) and tcpdump (Free, Open Source).
Wireshark is the world's foremost network protocol analyzer. It lets you capture and interactively browse the traffic running on a computer network. It is the de facto (and often de jure) standard across many industries and educational institutions.
GNU Wget is a free software package for retrieving files using HTTP(S) and FTP, the most widely-used Internet protocols. It is a non-interactive command line tool, so it may easily be called from scripts, cron jobs, terminals without X-Windows support, etc.
Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data.
tcpdump is a common packet analyzer that runs under the command line. It allows the user to intercept and display TCP/IP and other packets being transmitted or received over a network to which the computer is attached.
MetaProducts Offline Explorer is a Windows XP/2003/2008/Vista/7/8/10 program that allows you to download an unlimited number of your favorite Web and FTP sites for later offline viewing, editing or browsing.
macOS application that automatically downloads websites from the Internet. It does this by asynchronously copying the site's webpages, images, PDFs, style sheets, and other files to your local hard drive, duplicating the site's directory structure.