Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
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
Calendify - Calendify is an event community where you can share, publish, and subscribe to event calendars. It helps you to stay informed about what you are interested in and what is yet to come.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.