Planning to attend a local conference, I went through all the lectures and workshops that would interest me and wanted to add them to my calendar. Thankfully, the conference website has iCalendar files available, one for each event.
I organise my agenda with Google Calendar, but I discovered that it is not possible to just import all of these .ics files at once.
After a quick search, I discovered there were some small command-line scripts or windows executables available to merge several .ics files into one, but none of them was a simple and painless website.
This is why I decided to make a website for just this very specific usecase! Find it here, at: https://icsmerger.com