Umnico is described as 'The omnichannel messaging solution and the ultimate tool for managing customer communications. With support for over 25 business messengers and social media platforms, all accessible from one central chat-center, you can streamline your customer interactions like never' and is a instant messenger in the social & communications category. There are more than 10 alternatives to Umnico for a variety of platforms, including Mac, Android, iPhone, Windows and Linux apps. The best Umnico alternative is Pidgin, which is both free and Open Source. Other great apps like Umnico are Beeper, Ferdium, Franz and tawk.to.
tawk.to provides excellent services. I dealt with them to purchase a live chat service, and their services were highly efficient, but they only lack some development.