The concept of open innovation or using both inflows and outflows of knowledge to improve internal innovation [1] is well studied in Information Technology (IT) and Information Systems (IS) areas after the 2000s [2, 3]. The application of this concept has gone beyond the technical or everyday tasks such as open source software (OSS) or crowdsourcing in organisations. Recently, the open innovation concept has been combined with a decentralisation trend in strategic planning research [4], leading to a new concept called open strategy [5]. The new interdisciplinary concept of open strategy calls for increasing inclusiveness: receiving strategy ideas from people outside of the management team; transparency: providing people outside the management team with access to strategy input, process and outputs and use of IT tools in one or several activities required to formulate the strategic plan [6, 7]. Open strategy has been documented in many case studies, and various benefits are reported, including creating a dialogue about strategy [8], leveraging customers’ knowledge for strategy formation [9], increasing innovation and creativity [10, 11], better approval of strategy [12] and better firm performance [13-15]. Following reports in the literature about the usefulness of an open perspective for strategic planning, a vast body of literature has formed, and different aspects of this topic are investigated. For example, participation behaviour of stakeholders [14], strategising technologies [10, 16], associated risks [17] and outcomes of open strategy [18-20] have been widely reported in the literature on both the IS and management. Furthermore, numerous case studies of open strategy have been published [8, 21-23], which focus on potential opportunities and challenges in this topic area. Although the body of research around the open strategy topic has been useful to investigate many aspects of the phenomena, extant studies are primarily descriptive rather than prescriptive, and for this reason, only few process models [7, 24] are proposed, which claim to implement the notion of open strategy. Further, these studies are either theoretical or applicable only to a specific context and overlook important aspects such as specifications of a planning system. Consequently, we have little understanding of how an organisation can design and implement an Open Strategic Planning (OSP) system. This gap in our understanding is reflected in previous studies as ‘micro details of strategising’ using an open approach [6] and many other calls for prescriptive studies [7, 8, 12, 25]. The challenge in prescriptive OSP research is to prescribe how an OSP method can satisfy both social and technical requirements simultaneously [23, 26]. From a social perspective, an OSP methodology should focus on challenges such as commitment and disclosure in the strategy process [15], requiring a strong theoretical base. From a technical perspective, organisation of strategy resources including the stakeholder and planning system should fulfil the concept of OSP in terms of both process and artefact.