As admin create a new course Upload a few file resources (different types) like a pdf file, a txt, mp3, mp4 ... to the course. In each of the resource settings, enable the "Show type" option. Enrol any user in the course (not admin) As admin, enable "Mobile services": Site administration ► Mobile app ► Mobile settings Create a Token in the mobile app service for the user enrolled in the course Click on Site administration ► Plugins ► Web services ► Manage tokens Open the console an execute this new curl request, replacing wstoken with the token you just created and the site url with yours. Replace also the courseid with the course you created. curl 'http://localhost/m/stable_master/webservice/rest/server.php?moodlewsrestformat=json' --data 'courseid=2&wsfunction=core_course_get_contents&wstoken=3af67232a7596ceb658df4db329e5ad6' --compressed | python -m "json.tool" Check that for any module returned by the WS, you have a customdata field, displaying serialized data, like this: "a:3:{s:10:\"printintro\";i:0;s:8:\"showtype\";i:1;s:11:\"filedetails\";a:2:{s:4:\"type\";s:9:\"Text file\";s:8:\"mimetype\";s:10:\"text\/plain\";}} but displaying the correct mimetye depending on the type of the file, for example, for a PDF should be something like: application/pdf As admin in the sitem edit the settings of any of the resources you uploaded and disable the "Show type" option Execute again the CURL request and check that the customdata field does not containg the mimetype information for the resource you edited.