DOFbasen is an online database for bird observations in Denmark (www.dofbasen.dk), administrated by Dansk Ornitologisk Forening DOF/BirdLife Denmark. DOF is a NGO with ca. 18,000 members working for increasing the knowledge and protection of birds and their habitats in Denmark and abroad (www.dof.dk). The data are collected by volunteers and apart from bird observations also includes observations of mammals, amphibians, reptiles and butterflies. Most data are casual records, meaning that not all species and individuals seen by the observer necessarily have been reported. Rare and unusual bird observations are subjected to quality assessment by two Rarity Committees and observations under evaluation or dismissed are not included in this dataset. Furthermore, observations possibly requiring evaluation, but not yet processed, are excluded. The data can be used freely for non-profit purposes including scientific analysis if cited appropriately. We would appreciate receiving copies of any publications using our data to use for motivating the volunteers in their data collection. All images and other media associated with the records are copyright of the observer. A small number of vulnerable breeding bird observations have their precision blurred by rounding the coordinates and setting the uncertainty to 25 km. The full dataset is updated on a weekly basis, but not including data with an observation date within the last 7 days.