This app enables Dark mode for older phones. Namely devices that run below Android Oreo. It inverts colors of text and background thus forcing dark mode.

Warning: This app doesn't work on every devices. Although it works on most Xiaomi and Samsung devices. We encourage users to try it out to check if it works on your device.
Karbonn devices doesn't support this feature currently we are working hard to make sure we get to every devices with following updates. Please be patient and regret the inconvenience caused.

You need to restart your phone and relaunch the app again for the changes to take effect.