MMST WS 2017 -2018 Gruppe 5.2 Hamza Ben Hassen, Yu-Hsiang Lin, Bilík Šimon, Peter schweinitz the index.html file should be run inside a local server along with the R43ple Backend and not simply opening the file. Otherwise queries to the backend will always fail. On chrome this extension can be useful to run an html file locally: Web Server for Chrome