GNU Wget is a free software package for retrieving files using HTTP, HTTPS and FTP.

DownThemAll is a Firefox plugin that allows users to download all the links or images contained in a webpage.

ScrapBook is a Firefox extension, which helps you to save Web pages and easily manage collections. Major features are:

* Save Web page

* Save snippet of Web page

* Save Web site

* Organize the collection in the same way as Bookmarks

* Full text search and quick filtering search of the collection

* Editing of the collected Web page

* Text/HTML edit feature resembling Opera's Notes

SiteSucker is OSX and iOS software that can download an entire website, including images and videos.

Heritrix is web crawler used by the Internet Archive, which provides a web-based user interface after initial configuration on a Linux machine. Also used by the Library of Congress, Heritrix captures metadata in the Web ARChive (WARC) format.

HTTrack provides an easy-to-use interface for downloading websites-- including HTML, images, and other files-- or update a copy of a previously-downloaded site.