/bull-E/ Bulle is a modern solution for mocking HTTP API’s. Bulle can be utilized to create mock API endpoints for development purposes or for general testing. Preface I found myself developing applications where we had decided on the front-end technology, but were still contemplating on the backend technology. In these situtations, we started work on the front-end nontheless, and as with almost any modern web application, the front-end utilizes data acquired from the API.