I'm looking for a self-hosted alternative to Trello, primarily with the ability to set due dates for items across multiple boards, but have a single consolidated calendar showing due dates across the boards. Mattermost Boards does not offer this. Any ideas?
This thing has a ton of features and is worth checking out. There's a zillion options and settings for it too. I use it internally but I'm not sure if it can do the single calendar thing you're asking.
I used Kanboard for years prior to switching to a SaaS product for my sign shop. It was great for tracking the fabrication of projects in different steps.
Kanboard is currently my choice. You can install a couple plugins to make it look more modern and combine boards but it has almost all the features I wanted.