Apache Karaf might be a bit more popular than Kayako. We know about 1 link to it since March 2021 and only 1 link to Kayako. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
One we used at a previous place, Https://kayako.com/ Small company, I'm sure there was not much effort put in customizing it. No idea on pricing but wouldn't expect it to be on the high side. Source: about 2 years ago
Apache Karaf with OSGi works pretty nice using annotation based dependency injection with the declarative services, removing the need to mess with those hopefully archaic XML blueprints. Too bad it's not as trendy as spring and the developers so many of the tutorials can be a bit dated and hard to find. Karaf also supports many other frameworks and programming models as well and there's even Red Hat supported... Source: about 3 years ago
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Docker - Docker is an open platform that enables developers and system administrators to create distributed applications.
LiveAgent - LiveAgent is a fully-featured web-based live chat and help desk software. It harnesses the power of a universal inbox, real-time live chat, built-in call center, and a robust customer service portal. Start your free 1 month trial today!
Apache ServiceMix - Apache ServiceMix is an open source ESB that combines the functionality of a Service Oriented Architecture and the modularity.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Google App Engine - A powerful platform to build web and mobile apps that scale automatically.