Todo-Backend lists many implementations of the same REST API with different backend-oriented Web development frameworks.
I’ve documented the way I did it in the project’s documentation in details, for those curious about Symfony development of a very simple REST API (JSON based). See its README file (of course redacted with the mandatory org-mode ;).
You can find the rest of the code here : https://gitlab.com/olberger/todobackend-symfony4.
AFAICS api-platform offers a great set of features for Linked-Data/REST development with Symfony in general. However, some tweaks were necessary to conform the TodoBackend specs, mainly because TodoBackend is JSON only and doesn’t support JSON-LD…
Oh, and the hardest part was deploying on Heroku, making sure that the CORS headers would work as expected :-/