One-Handed Mode by XDA-Developers is the first and only app that replicates the iOS Reachability feature without requiring root access or a custom ROM.

One-Handed Mode lets you reach your status bar and action bar of any app without having to stretch your hand. It does this by moving the entire screen down to a smaller window.

This app uses a floating, movable bubble that toggles One-Handed Mode whenever it is pressed. There are also other ways to toggle One-Handed Mode if you dislike the bubble.

Features

- Toggle One-Handed Mode through a Launcher Shortcut
- Toggle One-Handed Mode through a Quick Settings Tile
- Toggle One-Handed Mode through an intent
- Integration with Custom Navigation Bar app to add a navigation bar button to toggle One-Handed Mode
- Emergency reset button to safeguard your device
- Start service on boot
- Automatically adjust DPI to better fit screen contents
- Customize One-Handed Mode window, support for left-handed window
- Drag to dismiss bubble
- Disables One-Handed Mode on lock screen, when pressing home button, or when in landscape mode

Warning!

Many applications are not fully compatible with One-Handed Mode, and will show a large blank space between the status bar and the window. This happens because those applications are not built for a variable screen size, and is a limitation of Android itself and not our app. We recommend that you do not customize the One-Handed Mode window so you can avoid this problem for the most part.
From version One-Handed Mode 27:
Minor bug fixes
All versions
November 27, 2017
November 10, 2017
November 3, 2017
October 27, 2017