Cal.diy
Online appointment scheduling system.
Self-hosted Booking and Scheduling software
Event scheduling, reservation, and appointment management software.
10 apps, ranked by GitHub stars weighted by maintenance health.
Rallly
Create polls to vote on dates and times (alternative to Doodle).
Easy!Appointments
Allows your customers to book appointments with you via the web.
Hi.Events
Event management and ticketing platform for conferences, concerts, and more. Offering customizable event pages and embeddable ticket widgets.
QloApps
Customizable and intuitive web-based hotel reservation system and a booking engine.
Alf.io
Ticket reservation system.
LibreBooking
Resource scheduling solution offering a flexible, mobile-friendly, and extensible interface for organizations to manage resource reservations.
OpenSlides
Presentation and assembly system for managing and projecting agenda, motions and elections of an assembly.
Seatsurfing
Webbased app to book seats, desks and rooms for offices.
Chobble Tickets
Event ticketing with QR check-in and encrypted attendee records. The complete product is AGPL-3.0 with no open core and no branding requirement, and it runs as an edge script without an always-on server (alternative to Eventbrite).