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Time Slot Booking Calendar PHP - Time Slots Booking Calendar PHP for online appointment booking and class scheduling.
Motion Firefox - All-in-one time management tool in Firefox
Dudle - Dudle is an online scheduling application, which is free and open source.
Taskable - Using multiple work apps leads to tons of context switching, breaking flow and killing productivity.
Pulse 24/7 - Booking & scheduling mobile app for service providers