I love the fact that it's open source, and well documented. I am currently hosting my own instance at https://jitsi.mastodo.ch/ and I plan to offer it as a free alternative to zoom, citrix, etc.
I've been working on https://yakondi.com which helps people around the globe get more out of their travel experience. Noone really want to travel right now - so COVID19 means we are focusing less on marketing and more on development and clearing our feature backlog. The technology stack is pretty simple (MySQL, Java REST & Angular) but I've also been experimenting with Jupyter and Dataiku for analytics of usage behavior. If you are not already familiar with our service, yakondi.com is a free network of locals and experienced travelers who will help you organize your next trip. It already connects 1000s of travelers across the globe and provides users with unique and tailored travel advice.