To download chrome browser for offline installation, refer below link
https://www.google.com/chrome/browser/desktop/index.html
Offline Installer
Offline Installer – Skype for computer
For windows: offline installer
For other platforms:
OfflineInstaller – Mozilla Firefox browser
Latest version :
https://www.mozilla.org/en-US/firefox/all/
Earlier versions :
Chose required version | OS [Linux/mac/win32/64] | chose language [en-us] and then download the file to install.
Multiple versions of Firefox browser on single machine :
If you want to install any version of firefox other than your default path, then chose “custom” and enter directory [folder path other than the default path] to install and continue installation.