Ungoogled Chromium

Ungoogled Chromium does NOT work with a classical installation of Flatpak like
sudo apt install flatpak

You must add the repository (at least for Ubuntu). See the link:

I suggest to add this information on the flathub page for people because this information does not appear here:
For people who want to add extensions in Ungoogled Chromium, this is turned off by default so to change this behaviour:
1- Go to
and change it to:
Always prompt for
2- Chrome Web Store
3- choose your extension, for example ublockorigin and copy the url, so:
uBlock Origin - Chrome Web Store
4- go to this website to extract the extension of ublockorigin:
click on “Start for free”
copy and paste the url of ublockorigin
click on “Download”
click on “Get .CRX” (.crx file, the ublockorigin file)
Click on “Add extension”

Done !

I just use Chromium Web Store.