Pixly - Pixel Art Editor-app
It has many useful features, and its design was made with phones and tablets in mind.
Here's a quick list of the features you may find in Pixly:
• Animations with onion skinning;
• Mini view with customizable level of zoom for quick preview;
• Dropbox and Google Drive integration;
• Controls intuitive for touchscreen;
Try pinching with two fingers to move and zoom the artboard, or pinching with three fingers to change the brush size!
• Contextual tools;
• Undo, Redo and History;
• Social features (Share, Twitter @DailySilhouettes and @PixelDailies);
• Text drawing;
• Color ramps;
• Transparent and non transparent background;
• Arcs and Curves;
• Real time image tiling;
• Symmetry with customizable mirrors;
• Lots of color effects;
• And more!