The aim of this study is to develop a semi-quantitative, web-based food frequency questionnaire (eFFQ-CH), using the menuCH photo book and the framework of a food frequency questionnaire developed at ZHAW Wädenswil. The development work will be based on results of the menuCH survey, the first national, representative nutritional data of the Swiss population. This unique approach will deliver a web-based dietary assessment tool for an adult population in Switzerland with advantages over other existing tools. Following a multi-stage approach, we first aim to use menuCH results to guide the development of the new composite FFQ. In this process, we will also consider suggestions from experts in other language-regions in Switzerland. Based on these inputs, the FFQ will be optimized for structure, food items, photographs and other aspects of respondent usability. The tool will be implemented into a state-of-art content management platform, offering many advantages for research applications. A validation study will be conducted in the German- and in the French-speaking parts of Switzerland by comparing it against a 3-day food record.