I appreciate the smaller indie developers, particularly in the Apple world, who specialise in a certain field and do it well, and take pride in being accessible. Rogue Amoeba is one. Their audio products are one of the best advertisements for Mac. Agile Tortoise is another, with the fabulous Drafts app. And another is Flexibits, who make the Fantastical Calendar app. This is a sound investment for management of the several calendars I keep. And they care a lot about #accessibility.
I use their Openings and proposals feature regularly in my professional life. Now they have added RSVP. Here’s the explanation from their blog. If you’ve not checked out Fantastical yet, I did a demo on Living Blindfully and they have plenty of videos and help guides. I highly recommend it.

flexibits.com/blog/2024/10/rsv…