Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
Zoho Backstage - Plan, run, and analyze your event— all from one place
Zapier - Connect the apps you use everyday to automate your work and be more productive. 1000+ apps and easy integrations - get started in minutes.
Meetup for iOS and Android - Discover groups that are all about the things you love
n8n.io - Free and open fair-code licensed node based Workflow Automation Tool. Easily automate tasks across different services.