This answer shows how to use Google Keep as a standalone web app in the browser (Chrome/Chromium/Firefox).

Google Chrome/Chromium

Try it in the terminal

There is a command line -app= option you can try. Open a terminal and enter

google-chrome -app=https://keep.google.com

This will open the Keep web page without tabs, the address box, menu, toolbar, or the installed chrome extension icons.

It looks pretty much like a desktop Google Keep app. If you like this approach, follow the next steps.

Create a desktop launcher

Create a desktop launcher file in $HOME/.local/share/applications/ folder with the following text.

[Desktop Entry]

Version=1.0

Name=Google Keep

Exec=/usr/bin/google-chrome -app=https://keep.google.com

StartupNotify=true

Terminal=false

Icon=google-chrome

Type=Application

I have kept the Chrome icon above. You may want to change to something more suitable.

Name this file keep.desktop and save it.

Now you should have a searchable desktop app for Keep.

The GUI way using Chrome

1. Open https://keep.google.com in Google chrome


2. Click on the three vertical dot menu on the top right corner


3. Click on More Tools > Create Shortcut....


4. Check the box Open as Window and then the button Create.

That is pretty much it.

Hope this helps

Firefox

First, install Linux Mint Webapp Manager in Ubuntu.

wget http://packages.linuxmint.com/pool/main/w/webapp-manager/webapp-manager_1.2.8_all.deb

sudo apt install ./webapp-manager_1.2.8_all.deb

Now open Webapp Manager, and click on the add button.

Now, add information about Google Keep.

(The icon is named chrome-google-keep in the Papirus Icon theme. In case you don't have this icon theme, you can manually download the icon from internet and add it)

Now, Google Keep should show up among your apps.