Interoperability is a key enabler for the accelerated digital transformation of cities and communities across the globe. This concept is promoted by both the European Commission (through the Living-in.EU movement and by Interoperable Europe, the European Commission’s open stop shop for e-Government), and by the UN (though U4SCC, a collaboration of 17 UN bodies coordinated by ITU, UNECE and UN-Habitat in support of SDG 11.) Technical interoperability depends on the use of open standards and technical specifications, and deployment of city platforms that allow for the roll-out of integrated digital solutions for efficient and effective management of infrastructure, data and services in cities, to tackle interlinked challenges for greater resilience and sustainability. Further benefits for cities and citizens include reducing deployment costs for public administrations and allowing co-creation of solutions with citizens for human-centred services and more sustainable and inclusive cities in line with the New European Bauhaus objectives. The European Commission publication ‘Proposal for a European Interoperability Framework for Smart Cities and Communities,- EIF4SCC’ is a reference document that explains the different aspects of interoperability (technical, semantic, legal, organisational, and cultural) and provides use-cases and good practice examples. The forthcoming U4SSC deliverable 'New architecture for sustainable, digital development' will also provide an excellent framework for interoperability, paving the way lower cost, values-preserving digital tools for deployment in cities and communities globally. The Minimal Interoperability Mechanisms (MIMs) developed by OASC and endorsed by both Living-in.EU and U4SSC, are a set of set of practical capabilities based on open technical specifications that allow cities and communities to replicate and scale solutions globally. *Living-in.EU was established in 2019 by cities and city organisations in the EU and is supported by the European Commission and the EU Committee of the Regions, based on the principals set out in the Join, Boost, Sustain Declaration. The movement now has more than 110 signatories at city, regional and Member State level, and over 100 supporters from the business, research and non-governmental sector.