Manage Blog Posts for Multiples Sites w/ 1 login?

I write and/or manage wp sites for lots of different organizations. I waste so much time going to each org’s website and logging in to add a new post or update plugins.

I’m trying to figure out if something exists that allows me to connect all the WP blogs I do things for and just manage them from a single login dashboard. (plugin or 3rd party website perhaps?)

I know there are a few “wp management” tools out there but they seem to only allow admin type management stuff (updates, backups, mal-ware detection) I need to be able to publish and edit posts. The other admin stuff would be a bonus but the posting is the important part that I can’t seem to find for all my hours of internet searching.

Any thoughts, suggestions or help would be deeply appreciated!