Front and back end teams will often agree on a "contract" about how a given application and its API should behave during the software design process. Each team can then work on their parts in parallel for efficiency. Eventually the teams will complete their required parts, and then the two teams will spend a brief period of time integrating the parts and testing the application.

Teams that work well together and implement their parts as agreed can often save time (and costs) using this strategy.

Software developers typically define a specification and document a RESTful contract of the APIs that are needed. These documents typically detail each aspect of your desired resources and operations. Following this blueprint will make it easier to know when the parts of the system are "done", and ready to be integrated.

Using mock data and contract, implement an API server using ExpressJS. You may find it helpful to use Postman, to verify your code is working as expected.