The web-extension is intended for interaction with the CA users signature web-library. For the web extension to work, you need to install additional software according to the links for the corresponding OS: Microsoft Windows: https://iit.com.ua/download/productfiles/EUSignWebInstall.exe Apple macOS: https://iit.com.ua/download/productfiles/EUSignWebInstall.pkg Linux (Debian\\Ubuntu) 32-bit: https://iit.com.ua/download/productfiles/euswi.deb Linux (Debian\\Ubuntu) 64-bit: https://iit.com.ua/download/productfiles/euswi.64.deb Linux (RHEL\\CentOS) 32-bit: https://iit.com.ua/download/productfiles/euswi.rpm Linux (RHEL\\CentOS) 64-bit: https://iit.com.ua/download/productfiles/euswi.64.rpm Linux (second) 32-bit: https://iit.com.ua/download/productfiles/euswi.tar Linux (second) 64-bit: https://iit.com.ua/download/productfiles/euswi.64.tar