👋 Hi! I'm Hyunjun, a backend developer based in South Korea with 14 years of experience. I built a Spring Boot 3.2+ open-source library that lets you declare and manage external API channels entirely from YAML. It started in the travel industry The thing is, every OTA has different API specs. One pattern that shows up often is when the lookup host and the booking/payment host are separated . https://api-search.someota.com → product lookup, price check https://api-booking.someota.com → actual booking and payment Same OTA, but two endpoints — different auth tokens, different timeout policies. Once you have 10 or 20 such OTAs, the problem starts in earnest. Similar-looking @Bean declarations grow with the channel count — and double again for any channel with dual endpoints — honestly piling up. The limits of RestClient + @bean My first attempt was the obvious one: register RestClient (introduced in Spring Boot 3.2) as @Bean s. It was boilerplate hell.…