Desktop Messenger for WhatsApp is an unofficial WhatsApp add-on for browsers (Firefox, Chrome and Opera) that can display incoming messages, new posts and direct replies within browser add-on bar.
Although technically it isn’t actually a stand-alone desktop application that can sign-in directly to WhatsApp without mobile devices , it provides a quicker way to access WhatsApp Web without navigating to a separate window to use it.
It is available for different browsers :
For Firefox
For Opera
Once installed, an icon will show up.
Clicking on that will lead to the QR code authentication window.
From the mobile device, access WhatsApp settings > WhatsApp Web version and sign-in.
The add-on lists the settings for various mobile devices.
Once signed-in to web version, new message notifications will be displayed by the add-on and clicking on it will open the WhatsApp Web window directly in same tab.
This add-on can also be configured for dimensions as well as shortcut keys for quick access. Select the settings icon.
Then, configure shortcut keys and toolbar size as needed.
All done.