I need agency or team to build my startup SASS

Hi! I am looking for an agency or team to help build my startup software-as-a-service (SASS) application. The technology stack that I desire to use is JavaScript and prefer the React framework. For designs and styling, I have existing designs and a style guide to reference. If you think you are the right agency or team that can help me build my SASS application, please let me know. Thanks in advance.