There are many languages available that can be used to create cross-platform applications and these types of code applications are being created daily. Some of the more common languages that these applications use are Java, C, and JavaScript and each has its advantages and disadvantages. While JavaScript is easy to get started with, it is also easy to lose control of. C requires a lot of overhead to create complex applications such as memory management, and Java requires the Java runtime to be installed. As applications grow and become more complex, so does the need to produce maintainable code. TypeScript is a new open source language created to make web development easier and more reliable. In this chapter we will: