From the Slums of JSON is a real REST API that anyone can use for prototyping or testing. Rather than some gibberish pseudo-Latin, it features the words and wisdom of the Wu-Tang Clan.
FSJ is a Python/Django/PostgreSQL that uses a hybrid of Django Rest Framework and some custom architecture to create a learning and testing resource for people building out REST projects. Unlike other services, FSJ users are indeed updating a real database and getting correct responses, which allows for more efficient cursory testing and even automated testing.
The homepage also serves in reverse as a Postman-like interface to test a user's own REST API.
The deployed version of the application can be viewed at slumsofjson.herokuapp.com.
To run the application after downloading or cloning, simply install all the dependencies in requirements.txt and start the server with $ python3 manage.py runserver.