We all used open source projects every day such as npm packages, editors, web applications, and even operating systems... Have you ever thought of building one of your own? In this talk, I will share my journey building Jest Preview, from when it was just a vague idea, to currently a well-adopted library to help frontend engineers write tests faster. I will share with you how to come up with an idea for a project to work on, what struggles you have to overcome as an author of an open source project, how to manage time efficiently, and how you get attention from engineers around the world. Also, I will give you some advice if you are interested in making your first contribution to the open source community. Finally, I will demonstrate how Jest Preview helps you work more efficiently and with more confidence as a frontend engineer.