We're hosted by default, and give a lot of customisation options, but if you find yourself constrained by them we've open-sourced our front-end (Django - https://github.com/microcosm-cc/microweb ) and the whole site and full functionality is through an API ( http://microcosm-cc.github.io/ )... so you can deploy your own front-end, delete anything you don't want, and add anything at all that you do want.
We're currently keeping the storage layer closed though. We have an open and ongoing debate about whether to open that in future. We want to do a lot of things that improve the user experience and doing so requires an ever more complex back-end. Things like replying to email notifications putting the reply against the thing you were notified about, or providing interfaces through other protocol (events get surfaced through webcal, all content through IMAP, etc). As it's early we want to get on with building that without someone deploying the backend and freaking when we change the requirements ("you now need to add email gateways, MX records, and your infrastructure diagram now has these added boxes, etc"). When we've done most of that we'll return to whether that should be, or needs to be, open.
We're currently keeping the storage layer closed though. We have an open and ongoing debate about whether to open that in future. We want to do a lot of things that improve the user experience and doing so requires an ever more complex back-end. Things like replying to email notifications putting the reply against the thing you were notified about, or providing interfaces through other protocol (events get surfaced through webcal, all content through IMAP, etc). As it's early we want to get on with building that without someone deploying the backend and freaking when we change the requirements ("you now need to add email gateways, MX records, and your infrastructure diagram now has these added boxes, etc"). When we've done most of that we'll return to whether that should be, or needs to be, open.