Digital questionnaire platform in the Danish Blood Donor Study

•The Danish Blood Donor Study was established in 2010 and by the fall of 2015, 100,000 Danish blood donors had been included.•At inclusion, plasma and blood for DNA analyses are collected and saved in the biobank and all participating donors have completed a four-page paper-based questionnaire on health related issues.•To be more cost-effective, we have developed and implemented a digital tablet-based questionnaire platform, using the open source survey software tool LimeSurvey.•Here we describe the details of methods for the platform which enables a faster and more flexible procedure to collect valid questionnaire data from participating donors.•The overall system can be used around the world by the use of internet connection, but the level of security depends on the sensitivity of the data to be collected.