Grammarly offers a mobile keyboard that allows you to access writing suggestions on Android and iOS devices.
All iOS devices running iOS 9.3 or newer are supported, which means that you can use Grammarly on all iPhone, iPad, and iPod Touch models. You can install Grammarly for iOS on your device by following these instructions.
As for Android, Grammarly is compatible with all devices running Android 5.0 (Lollipop) or newer. Tablets are supported as well. To install the Grammarly Keyboard for Android, please follow the steps outlined here.