I am working on an application called Matterbase. It is very new and there is still a lot of work to do. I have decided to release the basics first in order to start using it myself. In short, I have always found a calendar too structured for my own liking and wanted a place where I could just jot down ideas & notes I had that are related to certain events or tasks etc.
As mentioned I have plans to add useful features like multi-user workspaces etc. to empower collaborative workflows in the future.
You can visit my MVP at https://matterbase.io.
I would love to answer any questions or take in any suggestions. Feel free to also reach out on twitter - @Hermann_Harris.