Many large-scale platforms for social coordination suffer from a lack of reuse and opportunities for domain-specific customisation, yet offer a soft-target single point of failure for security exploits. Moreover, they are mostly privately-owned by trans-national corporations, whose motives and values are sometimes distinctly different from their user communities, wherein Artificial Intelligence (AI) is often used as a means to abstract or reinforce pre-existing asymmetric power relationships and inequalities. To address these problems, this paper presents the development of a system comprising a platform (an extensible architecture for social coordination) and meta-platform (a system for instantiating the platforms), which maps a high-level architecture, design methodology and operationalisation model to a platform instantiation, according to five design “values” of data autonomy, sustainability, usability, customisability, and multiplicity. Each of these values can then be cross-referenced with three further supra-functional requirements - platform democratisation, knowledge codification and continuous self-improvement - which we argue offers a new approach to platformisation using the lens of ethical platformisation.