What language we should choose? And where we should be searching?

Hello!

We are getting together for a new project, to build a 2-way API connectivity tool for programmers experimenting with new forms of e-commerce, and merchants operating across a range of e-commerce platforms. We would be grateful for any programming language choosing tips. We are looking for an experienced Full-stack/API Engineer to join our small team, to help us move fast and build a low latency and highly secure data exchange. Ideally someone thats experienced in backend engineering and building scalable API products, but to also know Javascript, because of our frontend work which is underway. We are not sure which language would be the best for our backend in this case. Could anyone help suggest where else we could post this requirement to find a knowledgable programmer to join us with this project?

Have a nice day everyone!