Are your partners/friends etc. in different places and doesn’t have a common platform to let each other know of their Yes/No for a meeting? You can use this awesome web application to do it in a very easy fashion. How secure it is, i cannot comment, but if these details are fine to be seen by others, this seems very good option for doing just this.
Disclaimer:- There might be other sites which aids you do just this but this is my suggestion. I am not saying that this is the best solution though.
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