AskDev: Real-time group project collaboration tools?

Hey DEV! I’m in grad school, and I’m taking a course for the summer semester all about Education Technology. The class is structured almost like an independent study, where we spend the semester researching a topic of personal interest and producing something (original research, a tool to solve a problem, or some educational content). As a web developer with a long-time interest in accessibility, I’m exploring a few different angles for building a tool to address accessibility issues with online courseware (MOOC platforms, learning management systems, that kinda stuff).
So, I have a question for the community: are you aware of any software/web applications focused on long-distance group collaboration, such as for team projects and stuff? I’m looking for examples with real-time communication capabilities, file sharing (and ideally editing/reviewing) capabilities, shared notes, etc. I haven’t had a reason to use this sort of app in the past, so I’m not familiar with any popular platforms or anything. My first thought is the Google suite (Hangouts/Chat + Google Drive basically), but are there more focused platforms out there?
Thanks in advance!
To clarify, I’m not looking for a tool to use myself, I’m looking for tools to examine for accessibility, and I’m thinking about building an alternative myself. So I’m especially looking for full-featured combination tools if they exist, especially tools specifically aimed at coursework and student group projects.
And to clarify further, I’m definitely also interested in more general solutions that are often used by student groups for collaboration on school projects (e.g. G Suite, Slack), so let me know what you’ve used, especially if you’re a current student!