Clément Salaün contributed backend features to the formancehq/payments and formancehq/fctl repositories over a two-month period, focusing on API compatibility and secure integration. For formancehq/payments, he updated the connector template to align with the latest registry API, modifying the registry.RegisterPlugin signature and Plugin struct initialization in Go to reduce integration risk and support future API evolution. In formancehq/fctl, he implemented CORS support for the stack proxy by designing HTTP middleware that manages CORS headers and preflight requests, introducing a configurable allowed origins flag. His work demonstrated depth in Go, HTTP middleware, and network programming, emphasizing maintainability and security.