Inkster is a open-source headless cms.
The most comfortable way to set up Inkster is by using Docker and docker-compose. Simply run
$ docker-compose build
$ docker-compose run --rm web /app/migrate
$ docker-compose run --rm web /app/main add-user admin@example.com admin
$ docker-compose up
and then go to localhost:8000/graphql and play with the API.