Grammarly style layout story writing space - URGENT

I need a simple but efficient online word processor to host on my server. I'm looking something that replicates the style, look and feel of Grammarly's word processor. I don't need the grammarly style functions added, although if thats something you can do we can talk about extra costs for that. The goal of this project is to have a space where I can write and take notes, brainstorm, insert images and save all these documents in one place on my server/the cloud.