Numbas exams run entirely in the web browser. While that means that Numbas can run in a huge range of contexts, it also means that all of the information required to carry out marking and calculate scores is necessarily on the student’s device.
When a Numbas exam is run through a standard desktop web browser, it is possible to use the browser’s developer tools to view the source code, retrieve expected answers, or manipulate reported data. For this reason, we recommend that high-stakes summative assessments using Numbas should be delivered exclusively through a locked-down browser app, so that students don’t have access to this internal data.
There are several locked-down browsers available. Safe Exam Browser is an open-source option.