Build me a bespoke web based staffing calculator for contact centre environments (front and back office)

Lots of Excel based calculators out there (erlang C), but looking for something web based that multiple people can use simultaneously.
The back office part of it is rarely addressed in these calculators so want to address that at the same time.
Surprising how so many Excel based options don’t fit the bill and even more surprised there isn’t a web based version. Maybe prohibitively expensive? Hence trying to find out if there’s anyone out there fancies converting my current Excel versions into something much more modern.