Rails projects typically start out fairly simple, but evolve into more complex applications over time. In order to add a client-side framework or mobile application, creating a REST API might be necessary.

It’s really straightforward to create a new Rails API. However, it might be easier to add an API to an existing project. There is “right” way to do this, but there are some things to keep in mind that can make future development a bit easier.

Full blog post here: https://era86.github.io/2020/12/09/quick-tips-for-adding-a-rest-api-to-a-rails-application.html