Migrating from a propriatary Microsoft based stack to open source Linux based
A technical deep dive into licensing, cost structure, usability, and risk when moving from a Windows + Microsoft 365–style stack to Linux and open source applications.
1. What this migration actually changes
In most organizations, “Microsoft stack” on the desktop means Windows as the client operating system, Microsoft 365 (Office apps, OneDrive, Teams), and tight integration with Active Directory, Exchange, and SharePoint on the back end. Replacing this with open source affects the operating system, office suite, collaboration tools, identity, and lifecycle management in one move.
In a typical Microsoft-centric environment you will see:
1.1 Example target open source stack
An open source–centric desktop environment usually involves a Linux distribution on the endpoint, open source applications for productivity and collaboration, and either open source or cloud-native alternatives to Microsoft’s server-side components.
| Layer | Common proprietary stack | Typical open source alternative stack |
|---|---|---|
| Client OS | Windows 10 / 11 Enterprise on desktops and laptops | Linux desktop distributions such as Ubuntu LTS, Linux Mint, Debian, Fedora or openSUSE |
| Identity & auth | Active Directory Domain Services, Group Policy | FreeIPA or Samba-based AD compatible domain controllers, LDAP, Kerberos, SSSD, sudo-based configuration management |
| Office suite | Microsoft 365 Apps (Word, Excel, PowerPoint, Access), Visio, Project | LibreOffice or OnlyOffice for documents, spreadsheets and presentations; draw/diagram tools such as Draw.io alternatives and Inkscape |
| Email & PIM client | Outlook with Exchange Online or on-premises Exchange | Thunderbird or Evolution as desktop clients; back end via Postfix/Dovecot, Cyrus, or cloud mail providers |
| Collaboration | Teams, SharePoint Online, OneDrive for Business | Nextcloud, ownCloud, or Seafile for file sync; Matrix/Element, Mattermost or Rocket.Chat for messaging; open source wikis and knowledge bases |
| Browser & web apps | Edge and Chrome with Microsoft web apps | Firefox and Chromium-based browsers plus self-hosted or SaaS web applications |
| Endpoint management | Microsoft Endpoint Manager (Intune, SCCM), WSUS | Ansible, Salt, Puppet, or commercial Linux management; unattended-upgrades and distro-native tools for patching |
In practice, many organizations end up in a hybrid state: Linux on some desktops, Windows on others, and a mix of SaaS and open source server components. The rest of this article focuses on the implications of that transition: licensing, cost, usability, and risk.
2. Licensing models and governance
2.1 Open source licensing fundamentals
Open source software is defined by the Open Source Initiative (OSI) Open Source Definition as software whose license allows free redistribution, access to source code, the creation of derivative works, non-discrimination by field of endeavor, and technology-neutral terms, among other criteria.
OSI also maintains a catalogue of approved open source licenses, including widely used permissive licenses such as MIT and Apache 2.0, and copyleft licenses such as GPL and AGPL that require derivatives to preserve the same freedoms.
A key point in a desktop migration is that the operating system, office suite, and most supporting tools in a Linux-based stack will each be governed by their own licenses. These licenses are enforceable legal agreements, and obligations typically include attribution, inclusion of license texts, and in copyleft cases, disclosure of modified source code when distributed or provided as a networked service, as summarized in work such as Open Source Licenses and Legal Implications.
2.2 Proprietary desktop licensing pressure
Proprietary stacks use vendor-specific end-user and enterprise license agreements. Beyond per-device or per-user licensing, many Microsoft-based environments depend on Client Access Licenses (CALs), feature add-ons, and subscription plans with evolving use rights. A 2025 survey by Azul and the ITAM Forum found that 27 percent of enterprises now spend more than 500,000 USD annually resolving software license non-compliance, and 73 percent have undergone an Oracle Java audit in the last three years. Almost eight in ten have migrated or plan to migrate to open source Java alternatives to reduce audit risk and recurring licensing cost. See the Azul / ITAM Forum survey and coverage such as this analysis on ITPro.
2.3 Side-by-side: licensing characteristics
| Dimension | Microsoft / proprietary desktop stack | Linux + open source desktop stack |
|---|---|---|
| License fees | Perpetual or subscription licenses for Windows, Microsoft 365, and CALs. Upgrades and feature tiers often have additional charges. | Most desktop components (kernel, desktop environment, LibreOffice, Firefox, Thunderbird) have zero license fees. Some enterprise Linux distributions or support subscriptions are paid. |
| Redistribution rights | Redistribution usually prohibited except under specific volume or OEM agreements. Internal packaging is bounded by EULA. | Open source licenses generally allow redistribution of unmodified binaries, and often modified ones, subject to conditions like preserving license text and notices. |
| Modification rights | Reverse engineering and modification are usually restricted or prohibited. In-house patches to vendor binaries are uncommon and often unsupported. | Permissive licenses (MIT, Apache) allow broad modification and closed redistribution. Copyleft licenses require modified versions to remain under the same license if distributed, or to provide source when used as a network service (AGPL). |
| Vendor lock‑in | Tight coupling between Windows, Office, Teams, Azure AD, and proprietary formats (for example, legacy DOC/XLS macros, Exchange protocols). Migration often implies high switching costs. | Standards-based protocols and open formats such as ODF reduce lock-in. Analyses on digital sovereignty, such as Open Circle’s overview of digital independence and SUSE’s perspective on open source and sovereignty, stress this as a key strategic benefit. |
| Audit exposure | Formal vendor audits; non-compliance can lead to backdated fees, penalties, and mandatory true-up purchases. The Azul / ITAM Forum survey and related coverage highlight recurring six-figure spends on remediation in large enterprises. | Traditional vendor audits are rare, but license non-compliance (for example with GPL) can trigger lawsuits, forced code disclosure, and reputational damage, as illustrated in cases discussed in analyses of major OSS license lawsuits. |
| Legal complexity | Complex, but centralized around a small number of vendors. Terms change via product terms documents and online service descriptions. | Many different licenses in play across the stack. Organizations often need software composition analysis and internal policies to track obligations across MIT, Apache, GPL, MPL, and others. |
| Termination & risk | License terms can be modified, and products deprecated, at vendor discretion. Termination rights typically sit with the vendor. | Rights to use existing versions persist under the license, and forks remain possible even if a corporate steward changes course or re-licenses new versions. |
3. Cost and total cost of ownership
3.1 Macro view: why organizations adopt open source
The 2024 State of Open Source report from OpenLogic, the OSI, and the Eclipse Foundation found that 95 percent of surveyed organizations either increased or maintained their use of open source in the previous year. Only 5 percent reduced it, and “no license cost / overall cost reduction” emerged as the single most cited reason for adoption, at about 36.6 percent overall and roughly 51.5 percent among government and public sector respondents.
3.2 Concrete case studies
The French Gendarmerie Nationale began its open source transition by replacing Microsoft Office with OpenOffice.org across 90,000 desktops, then migrating browsers and email clients, and finally moving the operating system to Ubuntu (“GendBuntu”). By late 2013, around 65,000 workstations ran Ubuntu, and the organization reported lowering desktop TCO by about 40 percent and saving millions of euros in licensing costs. Details are available in the Gendarmerie Nationale case study from Canonical, OSOR’s open source observatory article, and the GendBuntu project overview.
Munich’s LiMux project migrated thousands of city workstations from Windows to a Debian-then-Ubuntu-based desktop with OpenOffice/LibreOffice, Firefox, and Thunderbird. The European Commission’s case study Declaration of Independence: The LiMux Project in Munich notes that short- and medium-term savings were not the main driver; the city aimed for long-term independence in how it spent its IT budget. Over a five-year period, the project’s budget-effective cost was 12.8 million euros, with expected savings of about 3 million euros on software licenses alone, and later statements by the mayor cited roughly 11.7 million euros savings compared with a pure Microsoft roadmap, as reported by PCWorld and Softpedia.
An IBM TCO analysis comparing a Linux-based collaboration stack with a Windows and Exchange setup for 100 users showed lower cumulative startup and ongoing costs on Linux, even before factoring in downtime and admin productivity. Supplementary calculations estimated Linux availability at about 99.95 percent versus 99.00 percent for Windows, fewer required patches per year, and an administrator being able to manage roughly twice as many Linux servers as Windows servers. The methodology and numbers are laid out in IBM’s Linux vs Windows TCO presentation.
3.3 License compliance as a cost center
Figures from the joint Azul and ITAM Forum survey on software licensing and coverage such as CIOL’s summary of the findings.
3.4 TCO structure: proprietary vs open source stack
| Cost category | Proprietary desktop stack | Open source desktop stack |
|---|---|---|
| OS and desktop licensing | Windows Enterprise licenses (per device or user), Software Assurance, VDA rights for VDI, and admin tools. | Distro subscription (if using enterprise Linux) or zero-cost community distributions; no per-device license fees for the OS itself in most cases. |
| Office and productivity licensing | Microsoft 365 plans per user for Office apps, Teams, OneDrive; Visio/Project as add-ons. | LibreOffice or OnlyOffice at no license cost; separate open source tools for diagramming, PDF editing, etc. Some support contracts or managed services may be purchased. |
| Server-side licensing | Windows Server, Exchange, SharePoint, SQL Server, Remote Desktop licenses, and CALs. | Linux server subscriptions where needed; open source mail, groupware, file sync, and web servers with no CAL concept. |
| Audit & compliance | Potentially recurring vendor audits and internal SAM projects; six-figure spends on remediation are common in large enterprises. | Fewer external audits but more emphasis on internal processes to ensure open source license compliance and avoid GPL/AGPL violations. |
| Hardware refresh cycle | New Windows releases and heavier clients can shorten refresh cycles and push upgrades when support ends. | Linux can run effectively on older hardware, extending device lifetime; this was noted as a cost driver in public sector migrations such as the Gendarmerie. |
| Training & change management | Incremental training between Windows versions and Office UI updates; users usually already familiar with the ecosystem. | Initial training on a new desktop paradigm, office suite, and collaboration tools. Case studies show a spike in support demand followed by normalization after one or two months per department. |
| Support & operations | Vendor-backed support with SLAs, plus extensive partner ecosystem and documentation. | Choice between community support and paid support providers for Linux and key applications. Admin productivity can be higher thanks to automation and scripting, but requires specific skills. |
4. Non-cost benefits of an open source desktop
4.1 Flexibility, transparency, and digital sovereignty
Open source software exposes its source code for inspection, modification, and redistribution. Analyses from organizations such as Open Circle, SUSE, and Red Hat highlight advantages such as lower or zero license fees, the ability to adapt software to specific requirements, independence from a single vendor, and a community-driven development model that accelerates innovation.
These perspectives frame open source as a foundation for digital sovereignty: organizations and governments can shape their digital infrastructure without being bound to proprietary cloud or software providers and can maintain control over data and security posture. This is reflected in national strategies and moves like Denmark’s decision to migrate public sector desktops towards Linux and LibreOffice for sovereignty reasons, as reported by Windows Central.
A feature in Le Monde on the “shadow army” of open source notes that free and open source software underpins roughly 80–90 percent of modern software stacks, from mobile and cloud infrastructure to AI frameworks. This aligns endpoint strategy with what is already true in many data centers and cloud-native stacks. See Le Monde’s overview of open source’s role in the digital economy.
4.2 Security characteristics
Security profiles for open source and proprietary software are not inherently better or worse; they are different. The 2024 Open Source Survey, summarized on the GitHub blog as Seven Years of Open Source: A More Secure and Diverse Ecosystem, reports that 82 percent of respondents consider “secure by design” practices important when deciding whether to use a project.
The 2024 State of Open Source Security report from Snyk highlights that supply chain practices such as SBOM monitoring and automated composition analysis are still immature, with no single practice used by more than about two-thirds of organizations. BetaNews’s summary, Open source supply chain faces security issues, notes that while security practices lag, open source communities often outpace proprietary vendors in vulnerability response times.
In desktop migrations, these characteristics matter because the operating system, browser, and office suite will be built upon open source libraries that are updated frequently. Patch automation and configuration management become central to compensating for the increase in component diversity.
5. Usability and end-user experience
5.1 Desktop environment and training
Modern Linux desktops such as GNOME and KDE provide graphical environments with familiar concepts: taskbars, application menus, system trays, and so on. The French Gendarmerie case study reported that, from an end user perspective, the transition to Ubuntu was “unexpectedly smooth,” with almost no additional training required because many applications (OpenOffice, Firefox) stayed the same and the interface was easy to adapt to. This is detailed in the Ubuntu Gendarmerie case study.
Munich’s LiMux project found that after initial training and a short period of elevated support requests, ticket volumes fell below pre-migration levels in departments that had completed the switch, according to the official LiMux case study. Political and organizational factors later led Munich to reintroduce Windows for many users, as described in PCWorld’s report on LiMux, underlining that user satisfaction is influenced as much by governance and communication as by the software itself.
5.2 Office suite comparison: LibreOffice vs Microsoft 365
LibreOffice is a free, open source office suite that offers word processing, spreadsheets, presentations, databases, drawing, and a formula editor. It runs on Windows, macOS, and Linux. Microsoft Office and Microsoft 365 provide a comparable set of tools under a commercial license, with strong cloud integration and additional components such as Outlook and Publisher.
LibreOffice can open and save the dominant Microsoft formats (DOCX, XLSX, PPTX) and supports a broad range of other file types, including direct export to EPUB as described in its EPUB export documentation. However, documents created in Microsoft Office may not always render identically in LibreOffice because of font differences and layout engines; this can cause issues in workflows that rely on pixel-perfect formatting or complex macros.
A 2025 comparison LibreOffice vs. Microsoft 365: Can Open Source Beat the Giant? notes that LibreOffice is completely free and works well on older hardware, while Microsoft 365 requires a recurring subscription but delivers integrated cloud storage and real-time collaboration that is difficult to replicate with standalone tools. Similar analyses from platforms like FinancesOnline and Software Advice stress that LibreOffice is privacy-friendly and offline by default, whereas Microsoft 365 depends on user accounts and collects usage data to improve its services.
5.3 Usability comparison table
| Aspect | Microsoft desktop stack | Open source desktop stack |
|---|---|---|
| UI familiarity | Most users have prior experience with Windows and Office. Ribbon UI and Teams are widely known. | Linux desktops can be configured to resemble Windows or macOS. Some users experience an initial learning curve. |
| Office feature coverage | Extensive feature set including advanced Excel modelling, macros, integration with Power BI and enterprise add-ins. | LibreOffice and similar suites cover core word processing, spreadsheet, and presentation use cases. Some advanced features and third-party add-ins are missing or implemented differently. |
| Document interoperability | Near-perfect compatibility within the Microsoft ecosystem. Some issues between different Office versions. | Good compatibility for simple documents; complex templates and macros may break. LiMux used guidelines and “head stations” with Microsoft Office as fallbacks. |
| Collaboration | Integrated chat, meetings, presence, co-authoring, and file sharing through Teams, OneDrive, and SharePoint. | Mix of tools (for example, Nextcloud, Matrix, Mattermost). Real-time co-authoring is possible but typically less seamless. |
| Performance and hardware | Optimized for recent hardware; heavier feature set can strain older devices. | Linux and LibreOffice can run well on older devices, extending hardware lifetime and deferring refresh cycles. |
| Support model | Vendor-backed support with SLAs, plus extensive partner ecosystem and documentation. | Community forums, mailing lists, and optional paid support from vendors or integrators. LibreOffice community support is extensive but not bound by commercial SLAs. |
6. Key risks and trade-offs
6.1 Application and document compatibility
The most visible risk on the desktop is incompatibility with Windows-only line-of-business applications and Microsoft Office documents that rely on macros, custom templates, or proprietary plugins. In the LiMux project, interoperability between OpenOffice and Microsoft Office was manageable for many documents, but complex files occasionally caused problems, and the city maintained guidelines and conversion stations with Microsoft Office to handle edge cases, as described in the LiMux case study.
Some organizations that experimented with large-scale desktop migrations later reintroduced Windows when specific applications or workflows could not be practically ported or replaced. Munich’s partial reversal in 2017 cited user dissatisfaction and software availability as factors, but an Accenture review and reporting in PCWorld point to organizational issues rather than purely technical shortcomings.
6.2 Skills, support, and culture
Moving to Linux desktops and open source applications introduces new operational patterns. Traditional Microsoft-oriented teams may need time to become fluent in distribution-specific packaging, scripting, and troubleshooting. Case studies such as the Gendarmerie and LiMux show that dedicated migration support teams, pilot departments, and “germ cells” of early adopters are important to spread expertise and reduce friction.
6.3 Legal and compliance risks in open source
Open source compliance has become a serious legal topic. The Journal of International Commercial Law and Technology article Open Source Licenses and Legal Implications summarizes how open source licenses impose obligations such as attribution, source disclosure for copyleft licenses, and patent clauses in licenses like Apache 2.0. Non-compliance can trigger injunctions, forced source code release, and monetary damages, as illustrated by enforcement actions against companies including Cisco and Orange.
As open source adoption grows, organizations increasingly adopt practices such as automated software composition analysis, license inventories, and SPDX-based bills of materials to track these obligations. Practical guidance on managing these risks appears in resources like FOSSA’s analysis of major OSS license compliance lawsuits.
6.4 Security and supply chain
The attack surface of a Linux desktop plus a diverse mix of open source applications is different, not necessarily smaller. The Snyk 2024 State of Open Source Security report indicates that many organizations have not fully implemented SBOM monitoring and composition analysis, and adoption of practices such as container scanning sits well below 70 percent. At the same time, the report notes that open source communities often fix vulnerabilities more quickly than proprietary vendors, emphasizing the need for responsive patch management rather than complacency.
6.5 Risk matrix
| Risk area | Manifestation during migration | Potential impact | Common mitigation patterns |
|---|---|---|---|
| Application compatibility | Key apps require Windows-only drivers, legacy frameworks, or proprietary plugins. | Users blocked from performing critical tasks; shadow IT and local workarounds emerge. | Retain Windows for certain roles; use VDI, remote app publishing, or Wine; prioritize web-based replacements over time. |
| Document interoperability | Complex Office documents render incorrectly in LibreOffice or OnlyOffice. | Broken templates, legal documents with layout issues, or analytics spreadsheets that no longer calculate correctly. | Introduce ODF-based templates, define interoperability guidelines, and maintain a small pool of Microsoft Office “conversion stations” as in LiMux. |
| User adoption | Perceived loss of functionality, friction with new UI, or lack of training. | Productivity dips, increased support calls, and political resistance, as seen in later debates around LiMux. | Pilot groups, champions, targeted training, and clear communication on benefits and trade-offs. |
| Operational skills | Operations team unfamiliar with Linux tooling and package ecosystems. | Misconfigurations, slower incident response, and inconsistent patching. | Dedicated upskilling programs, hiring experienced Linux engineers, and leveraging managed services or vendor support. |
| Open source license compliance | Untracked libraries with copyleft licenses in internal tooling or redistributed software. | Litigation risk, forced code disclosure, and reputational damage. | Central OSS policy, automated SBOM and composition scans, legal review of high-risk components. |
| Security & supply chain | Many components with varying patch cadences and security practices. | Exposed vulnerabilities if patching and monitoring are not systematic; increased burden on security teams. | Standardized base images, hardened baselines, automated updates, SBOM monitoring, and integration with vulnerability management. |
7. Migration patterns and phases
Successful public sector migrations provide a recurring pattern: start by replacing applications that have good cross-platform equivalents, centralize more workloads into the browser, then switch the operating system only when most workflows have become largely platform-neutral.
The Gendarmerie created a centralized intranet architecture, replaced Microsoft Office with OpenOffice.org, then moved to Firefox and Thunderbird, and only afterward committed to Ubuntu on the desktop. Munich’s LiMux project similarly used pilot departments and “germ cells” of 30–50 workstations inside each department before rolling out a Linux client more broadly, as detailed in the LiMux case study and the LiMux project overview.
8. Summary
Migrating an organization’s desktop environment from a Microsoft-centric stack to Linux and open source applications reshapes licensing exposure, cost structure, and operational risk. OSI-compliant licenses remove per-device and per-user software fees while introducing a need for structured open source governance, as captured in the Open Source Definition and related guidance from the Open Source Initiative. Case studies such as the French Gendarmerie and Munich’s LiMux show that, when executed with phased rollouts, careful attention to formats, and strong internal support, organizations can reduce long-term TCO, extend hardware lifetimes, and gain strategic independence over their software landscape.
At the same time, real risks exist around application compatibility, user acceptance, security, and license compliance. Surveys from 2024 and 2025 indicate that cost savings, reduction of vendor lock-in, and the perceived business value of open source continue to drive adoption, but that successful transitions depend on governance and technical discipline as much as on technology choice. The 2024 State of Open Source report, the Snyk security study, the GitHub open source survey, and legal analyses such as the JICLT article on open source licenses collectively show an ecosystem that is mature enough to carry mission-critical workloads, while still demanding active management of risk and compliance.
9. Simulate your migration with NEO Insights
To move from theory to data-driven planning, you can model these trade-offs against your own environment using NEO Insights. NEO Insights aggregates and normalizes software and infrastructure data so you can see how much of your estate is tied to proprietary desktop, productivity, and collaboration stacks versus open source or SaaS alternatives.
Within NEO Insights, you can run a NEO Migration Report to simulate what a move from a proprietary Microsoft-like stack to an open source / Linux desktop stack (and vice versa) would look like for your organization. This includes estimating changes in license exposure, projecting cost deltas across OS, office, and collaboration layers, and highlighting high-risk application dependencies where Windows clients or specific Microsoft components are still required.
That kind of simulation acts as a low-friction rehearsal: you can explore multiple migration scenarios, stress‑test timelines and scope, and decide where a hybrid model (with both Linux and Windows desktops) makes the most sense before committing to large-scale change.
