Finding Freelancers for Javascript Project

This project is for a potential project, we just want to see how much it will cost. We are a company that is currently working on a hardware project but wants to expand into software. We are wanting to find freelancers for a bot project like the Google Assistant. The developer needs to be familar with Javascript as the backend system is [login to view URL] ([login to view URL]). The bot created would be able to connect to weather, uber, open table and other APIs that consumers use everyday. How much would you charge for this?