HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
GNU Wget - GNU Wget is a free software package for retrieving files using HTTP(S) and FTP, the most...
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
WebCopy - Cyotek WebCopy is a free tool for copying full or partial websites locally onto your harddisk for offline viewing.
Platforma - Wireframe library of layouts and UI elements