Mockend for Frontends: mockend is available 📎
mockend was used to test / illustrate the "unidirectional dataflow" in the Web Components quickstarter.
The path: /crud exposes "Create Read Update Delete" functionality: the created JSON-objects are stored in memory
and are available for subsequent requests. With the /statuses functionality you can specify in the header the status code, what is helpful for 
fetch API tests. 
mockend also exposes the /echo resource which simple returns the payload passed as POST body.
All responses can be artificially delayed with the "delay-in-ms" header.
mockend ships as a fatjar and requires Java 11+ and uses functionality from the snail and statustest projects.