heise+ | Switching from M365 to Nextcloud a guide

Many organizations are increasingly looking for alternatives to Microsoft 365 due to rising licensing costs, additional charges for new AI features such as Copilot, and shrinking volume discounts. At the same time, regulatory pressures from laws like the GDPR, NIS2, and the EU Data Act have intensified. As a result, many companies are seeking solutions that offer better control both technically and contractually. Governments such as those in Schleswig-Holstein and Denmark argue that true operational freedom comes when an organization can extract its business data from a provider's environment whenever needed. In response to these demands, Nextcloud offers a modular open-source platform that allows for self-hosting on internal hardware or managed hosting through various European providers. These include major hosting services like Ionos, Hetzner, and Telekom’s MagentaCLOUD, along with specialized Nextcloud providers holding Premier Partner status. A migration from Microsoft 365 involves three main pillars: conducting a thorough assessment of all workloads, implementing changes in stages per department, and carefully testing the transition into production. The recommended migration sequence starts with identities and files, followed by groupware functions such as calendars, chats, and tasks, and finally email. Email accounts are typically handled last because they are deeply integrated into workflows, calendars, and external interfaces. For office components, mature server services such as Collabora Online and OnlyOffice are available. Starting in summer 2026, the European industry initiative Euro-Office will further expand this offering. Common challenges during migration include complex SharePoint permissions built over years, external sharing links that become invalid after switching platforms, and overlooked retention periods. Despite the complexity of the subject matter, which makes it difficult to cover all technical options exhaustively, it is clear that a complete migration away from Microsoft 365 is achievable using existing tools and methods. The tools and processes described here serve as examples of current possibilities. The Nextcloud ecosystem provides resources for nearly every aspect of migration, from mass data transfer and identity integration to specific cases within particular departments. While the complexity prevents a comprehensive overview of all technical options, it is evident that full migration from Microsoft 365 is feasible with the available means. The tools and procedures outlined here represent the current state of capabilities. Organizations considering a switch must first conduct a detailed inventory of their current workloads. This includes evaluating their architecture and selecting a suitable host. Options range from self-hosting on internal infrastructure to managed services offered by various European providers. Choosing the right host is crucial as it affects scalability, security, and compliance with regulations. Once the host is selected, the next step involves managing identities and permissions. Transitioning user identities from Microsoft 365 to Nextcloud requires careful planning to ensure seamless access without disrupting ongoing operations. Bridging mechanisms may be necessary to maintain continuity during the transition period. Additionally, setting up appropriate permission structures ensures that users retain the correct level of access post-migration. Groupware functionalities such as calendars, chat, and task management need to be evaluated for compatibility with Nextcloud. Solutions like Talk can serve as replacements for Microsoft Teams and email, while knowledge management systems can be adapted to fit within the Nextcloud framework. Automations and custom applications previously built using Power Apps require alternative approaches, often involving open-source tools or third-party integrations. Finally, executing the cutover involves meticulous planning to avoid disruptions. This includes testing all aspects of the new system before full deployment. Potential pitfalls include outdated SharePoint configurations, broken external links, and unconsidered data retention policies. Addressing these issues beforehand helps ensure a smooth transition. As more organizations seek greater autonomy and control over their digital environments, the shift towards platforms like Nextcloud represents a growing trend. With proper planning and execution, migrating from Microsoft 365 to Nextcloud is not only possible but also a viable strategy for enhancing flexibility and compliance in an evolving regulatory landscape.