A while back, WhatsApp launched WhatsApp Web, a web client that can be used through a web browser by synchronizing the mobile device connection. Whatsie uses WhatsApp Web, and it requires having WhatsApp Messenger installed and configured on your mobile device.
Besides being able to close the app to tray, the tray / AppIndicator icon is also used to notify the user about unread messages:
The application supports automatic but that's not supported in Linux if you install it from a package (deb or rpm). However, you can install Whatsie in Debian, Ubuntu, Linux Mint, and derivatives from a repository, which provides updates via Software Updater. A Fedora repository is also available.
If you prefer Telegram, see:
Download Whatsie
(deb, rpm, dmg, nupkg, Windows setup and source available for download)
sudo apt-key adv --keyserver pool.sks-keyservers.net --recv-keys 1537994D
echo "deb http://dl.bintray.com/aluxian/deb stable main" | sudo tee /etc/apt/sources.list.d/whatsie.list
sudo apt update
sudo apt install whatsie
Note that my instructions above are a bit different than the ones provided on the Whatsie GitHub page - most importantly, I modified the command to add the Whatsie repository to use a separate .list file under /etc/apt/sources.list.d/ instead of using /etc/apt/sources.list.
Fedora users can install Whatsie from a repository.
On Arch Linux, install Whatsie via AUR.
Report any bugs you may encounter @ GitHub.