In this chapter, we will cover the techniques and steps that will help us create Rust units in our existing applications that are written in other languages, such as C, Node.js, and Python. We will deep dive into the concept of foreign function interface, which helps us in writing bindings for a foreign code base. Rust outperforms many programming languages in the aspect of stability and safer parallelism. It would be ideal for production level application developers to try out Rust for building small units in the code, and test to see if there is a considerable amount of performance change. This chapter helps to facilitate these kinds of thoughts and ideas.