BabyWorld (available for iOS and Android) is an app filled with high-contrast flash cards for your baby's development and it saves you from buying cards, or, what I did before my baby was born, sourcing, printing out and laminating cards for her.
This free app contains 10 flashcards each in black and white, and first colours, and then you have a choice to buy 30, or 60. The app is suitable for newborns to one-year-olds, and I love that it also plays classical music with the flashcards for even more stimulation.
You can choose to manually play the cards, or get them shown via autoplay.
The app also has an extra feature that shows you what your baby sees. Select their age, take a pic of their room for example, and you'll see how your baby sees it. And if you think others might be interested, you can share the pic too via Facebook, Twitter or Instagram.