The promise of artificial intelligence and algorithms to make bureaucratic processes more efficient and minimise ‘subjective’ judgement and, hence, professional discretion in case management has recently resulted in the development and implementation of different kinds of algorithms in social work. In this paper, we analyse the ideas, developments and use of three ‘decision-support’-algorithms, developed for Danish municipalities within social work with vulnerable children and families. These algorithms are meant as support of professionals in their decision-making in respect of referrals. Building on recent studies on the effects of digitalisation on frontline work and professional discretion, we analyse the intentions, designs, and workings of decision-support algorithms in social work, specifically in casework with vulnerable children and families. We analyse what is meant by professionals in need of ‘decision support’ and how these algorithms reconfigure ideas about professional discretion. Through the analysis, we find that the algorithms are intended to support decisions by standardising casework, objectivising basis for decision, and by eliminating bias. Furthermore, we document the close relationship between the intentions of algorithms and the conception of professional discretion.