CADAS is an online server-client survey platform that allows the active collection of polling or observational questionnaire data in various ways (e.g.: visits in CAPI-mode or Mobi-mode, phone calls in CATI-mode, web links in CAWI-mode).CADAS Mobi user (Respondent or Interviewer - depending on given data collection method) can run and complete in off line mode any questionnaire / form created with the standard CADAS questionnaire editor using the Android driven mobile devices like: tablets, tablet PCs smartphones and handhelds.Our solution enables transferring questionnaires to mobile devices in a single file created in the common graphical questionnaire editing environment of the CADAS QET application, where CAWI, CAPI and CATI questionnaires are created for implementation on the CADAS Platform. Common tools and compatibility with CAWI and CAPI surveys greatly simplify the management of the project at all its stages. CADAS Mobi licencee (mostly - research agences) can use a wide range of features of the standard research project management tool for the CADAS Platform, the CADAS SCU (Research Operations Utility) client application. Interview results are stored on a memory card and can be uploaded to the server individually as required, sent directly after the interview is completed, or synchronized automatically later. The direct synchronization of interviews allows ongoing monitoring of the sample inflow and interviewers performance like with CAPI interviews conducted with laptops.