Rave Alert - Rave Alert is a multi-modal emergency notification system used by state and local governments, colleges, hospitals and universities.

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

DialMyCalls - The easy to use mass and emergency notification platform. Send a phone call, text message or e-mail to your entire list of people in seconds.

Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform

Call-Em-All - Call or send messages to friends and family members as well as other people who are online. The app allows you to create a message and send it out to multiple devices and pages.

pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features