Google is taking its sweet time giving Android a proper dark UI mode, leaving individual developers to pick up the slack. Speaking of Slack, that app is finally getting dark mode support, according to the company's website. No more frying your retinas if you have to pop into a chat room at night. In fact, you can stay up all night working now. Yay.
The dark mode toggle is under the main system settings. Just scroll down toward the bottom, and you'll see the "Dark Mode" entry. It's disabled by default, and activating it will cause the app to restart. However, Slack returns with an easy-on-the-eyes dark theme. It's not completely black, which is better for power consumption on OLEDs, but it's very dark gray.
Slack says the update is rolling out today, but we haven't seen it show up yet. At present, you can only experience dark mode in the beta version of the mobile app. The desktop app doesn't have dark mode support at all, but it's in the works.