HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
FileZilla - FileZilla is an FTP, or file transfer protocol, client. It lets individuals transfer single files or batches to a web server. For many years, FTP was the standard for website design. Read more about FileZilla.
Wget - GNU Wget is a free software package for retrieving files using HTTP(S) and FTP, the most...
Cyberduck - A libre FTP, SFTP, WebDAV, S3, Backblaze B2, Azure & OpenStack Swift browser.
WebCopy - Cyotek WebCopy is a free tool for copying full or partial websites locally onto your harddisk for offline viewing.
WinSCP - WinSCP is an open source free SFTP client and FTP client for Windows.