Yes, for me it was about web development. We had to build a web app that's about managing project resource. They provide all the data that we need. We can decide what database that we want to use, and what front end we want to use.

A tip before going into the hackathon, practice your api skill if you decide to do backend stuff. And practice some front end stuff if you want to help with the front end design. They let you choose what you want to do (frontend or backend), but you don't know who you will team up with, and you don't know what your teammate's background is, so it's better to be
prepared to do front end or back end to some extend if you want to ace it. But at the end of the day, they will assess you base on your provision for your team, so just do well on your part, no matter what you choose to do (frontend or backend). Try to help your teammate as well.