What are some alternatives?
When comparing osTicket and Zammad, you can also consider the following products
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
ZenDesk - Zendesk is a beautiful, lightweight help-desk solution.
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
UseResponse - Open-source, self-hosted customer feedback software, live chat and helpdesk system that you can install on your server. Organize documentation using knowledge base and get feedback from social networks with centralized system
Kayako - Help Desk Software and Customer Service Software by Kayako. Improve customer satisfaction, increase sales.
UserVoice - UserVoice integrates easy-to-use feedback, helpdesk, and knowledge base management tools in one platform that empowers users to speak and companies to understand.