In-depth knowledge of at least one backend programming language and framework.Knowledge of front-end technologies, such as HTML, CSS, and JavaScript, so that he can communicate with the front-end team. should be capable of managing a hosting environment along with the database administration.He should be capable of scaling applications to handle the load changes.should have enough knowledge of accessibility and security compliance.It's good for him to have an experience of version control, such as GIT.A backend developer is not expected to have command on every programming language. That is not possible for a human to have expertise in each of them. But they are expected to be experts in their opted language.