During Simplydigi project were organized so many online meeting that brought us to discover Rallly (https://rallly.co/), a simplydigi tool to plan and schedule group meetings on the fly according with the availability of others.
Rallly can be useful to make scheduling easier and to help finding the right date and time for a group of people to meet. It’s easy to set up the meeting details, with different date and time options, and invite others via email to pick the time in the schedule that works best for them.
As a scheduling app Rallly is a great place to start completly free with an open source application that works online without even the need of a registration.
More info about SimplyDigi project: https://www.simplydigi.eu/
More info about Rallly: https://rallly.co/