Passive income: NO

Custom API development for automation has the potential to generate passive income, but it is not guaranteed for everyone. Setting up systems for automation and potentially outsourcing tasks can help make this side hustle more passive over time. While some individuals have achieved passive income through this hustle, it is more common for a few outliers rather than the majority. It typically requires a significant initial time investment to develop the APIs and set up the necessary infrastructure. Success in earning passive income from this hustle depends on factors like demand for custom API development services, the quality of work delivered, and ongoing maintenance and support required. While it is possible for some to earn passively from this side hustle, it may not be a reality for everyone.