Hiring a functional testing developer ensures that your software behaves as expected and meets all user requirements. They scrutinize every function of your software, such as user interface, APIs, database, and security, to identify any errors or inconsistencies. They help in improving the quality of your product, reducing the risk of failures, and enhancing customer satisfaction. Their expertise leads to the efficient troubleshooting of issues, saving time and resources, and ultimately, contributing to the overall success of your software in the market.