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When launching an IT project, the choice of software almost always boils down to this question: should we go for an open‑source solution or a proprietary one? The issue resurfaces in management committees, developer discussions, and public calls for tenders. Yet the main difference between open source and proprietary software can be summed up in one sentence: access to the source code and the rights you obtain over it. This distinction, which may seem technical, has deep repercussions on costs, security, flexibility, and the digital strategy of an organization. Behind this fundamental criterion lie radically opposite philosophies, each with concrete strengths and limits. Here is a complete tour of the issue, to help you decide with full awareness.
The nature of the source code: accessibility versus confidentiality
The source code is the recipe for building a software product. Whether it is open or closed completely changes the user’s rights. This is the starting point for any serious comparison between the two models.
Open‑source code and free modification
An open‑source software makes its source code available to anyone who wishes to read, modify, or redistribute it. Think of Linux, Firefox, WordPress, or PostgreSQL: any developer can download the code, adapt it to his needs, and propose improvements to the community. This transparency allows thousands of contributors to spot bugs, add features, and fix security flaws.
In practice, a company that uses an open‑source CMS like WordPress can create its own plugins, alter the rendering engine, or adapt the system to a particular infrastructure. It does not need anyone’s permission. This freedom attracts both startups and large French administrations, which see it as a way to keep control over their tools.
Industrial secrecy and proprietary software lock‑in
Conversely, a proprietary software vendor keeps its source code confidential. Microsoft Office, Adobe Photoshop, or SAP deliver only an executable file: you can use the software, but you cannot see how it works nor modify it. The code is protected by copyright and often by patents.
This lock‑in follows a clear economic logic: the vendor protects its R&D investment and preserves a competitive advantage. For the user, it means total dependence on the supplier for updates, bug fixes, and product evolution. If the vendor decides to drop a feature or raise prices, the user’s recourse options are limited.
License models and usage rights
Beyond code access, the legal framework defines what you are allowed to do with a software. Open‑source and proprietary licenses follow very different logics.
Permissive and copyleft licences
The open‑source world offers two major families of licences. Permissive licences such as MIT or Apache 2.0 allow almost anything: you can embed the code in a commercial product, modify it without the obligation to publish your changes. That is why giants like Google or Apple heavily use MIT‑licensed code in their own products.
Copyleft licences, the most famous being the GPL (GNU General Public License), impose a strong condition: any derivative work must be redistributed under the same licence. If you modify GPL‑licensed software and distribute it, you must make your source code available. This constraint, sometimes perceived as a hurdle by companies, guarantees that improvements stay accessible to the community. The Linux kernel has been under GPL since 1991, and that mechanism has been key to its spectacular growth.
End‑User License Agreement (EULA)
Proprietary software relies on an EULA, the long legal text most users accept without reading. This contract precisely defines what you can and cannot do: number of authorized seats, prohibition of reverse engineering, geographic restrictions, usage duration, etc.
A typical Microsoft 365 EULA, for example, states that you do not buy the software but a revocable usage licence. The vendor retains total intellectual‑property ownership. This approach provides a clear framework but leaves little leeway for the user, who must respect sometimes‑stringent conditions under penalty of legal action.
Cost comparison and business models
Financial arguments always surface in the debate. Yet reality is more nuanced than a simple “free vs. paid” dichotomy.
Free software vs. paid support services
An open‑source software is generally free to download and use. But free does not mean costless. Red Hat, acquired by IBM for $34 billion in 2019, built its business on support, training, and certification around Linux. Canonical does the same with Ubuntu.
For a SME deploying an open‑source ERP such as Odoo Community, the software itself costs nothing, but integration, customization, and maintenance will likely require investment. Total cost of ownership (TCO) heavily depends on internal expertise. A strong technical team can dramatically reduce the bill, whereas an organization lacking expertise will need external specialists.
Licence fees and recurring subscriptions
Proprietary software usually follows per‑seat, per‑server, or increasingly subscription‑based models. Adobe switched its entire Creative Cloud suite to subscription in 2013, moving from a one‑time purchase to roughly €60 per month per user for the full package.
This model guarantees recurring revenue for the vendor and perpetual access to updates for the user. The downside: stop paying and you lose access. For a company of 200 employees using Microsoft 365 Business Premium at about €20 per user per month, the annual bill exceeds €48 000 – a figure that pushes many organisations to seriously reconsider open‑source alternatives.
Development, maintenance and security
How a software is developed and maintained directly influences its reliability and security. The two models adopt radically different approaches.
La force de la communauté et la transparence
A mature open‑source project benefits from hundreds, sometimes thousands, of contributors. The Linux kernel counts more than 15 000 developers from 1 500 different companies, according to the Linux Foundation. This diversity of eyes on the code enables rapid vulnerability detection. The Heartbleed bug in OpenSSL, discovered in 2014, was patched within days thanks to community mobilisation. This dynamic lies at the heart of the open‑source community.
Code transparency does not guarantee the absence of flaws, but it allows independent audits. The French ANSSI (Agency for the Security of Information Systems) actually recommends that public administrations favor solutions whose code can be inspected. When the code is visible, nobody can hide a backdoor without risking detection.
Responsiveness of specialised vendors
Proprietary vendors maintain dedicated security and support teams. Microsoft employs more than 3 500 cyber‑security engineers. When a critical vulnerability is found in Windows, a fix is usually rolled out via Windows Update within a controlled timeframe, after extensive testing.
The proprietary model also provides contractual liability. In case of a serious failure, the vendor can be held responsible – an option that generally does not exist for “as‑is” open‑source software. For regulated sectors such as banking or healthcare, this contractual guarantee weighs heavily in the decision‑making process.
Flexibility and digital sovereignty
Avoiding vendor lock‑in
Vendor lock‑in, or proprietary lock‑in, is one of the major risks of proprietary software. When a company stores ten years of data in a proprietary format, migrating to another solution becomes costly and risky. Proprietary formats, closed APIs, and integrated ecosystems create formidable exit barriers.
Open source offers a credible alternative. Open formats (e.g., ODF for office documents) and interoperable standards allow switching solutions without data loss. The French Interministerial Digital Directorate (DINUM) actively promotes open‑source adoption in public administrations, precisely to preserve the State’s digital sovereignty and reduce dependence on foreign vendors.
Sovereignty also has geopolitical dimensions. The U.S. Cloud Act permits American authorities to access data hosted by U.S. companies, even abroad. Choosing an American proprietary software thus acquires a geopolitical weight. Initiatives such as the European Gaia‑X project aim to build alternatives based on open‑source building blocks.
Synthesis: how to choose between the two models?
The choice between open source and proprietary software is never binary. The right approach depends on your context: internal technical skills, budget, regulatory constraints, need for customisation, and long‑term strategy.
Concrete criteria to guide the decision
- Internal skills : without a technical team capable of maintaining and adapting the code, a proprietary solution with integrated support is often more pragmatic.
- Budget : calculate the total cost of ownership over five years, not just the initial purchase or subscription price.
- Criticality : for a strategic tool, the ability to audit the code and avoid dependence on a single supplier may justify investment in open source.
- Interoperability : ensure the chosen solution uses open standards and protocols to avoid lock‑in.
Many high‑performing organisations combine both approaches. They run Linux on servers, use LibreOffice for everyday office work, yet keep specialised proprietary tools where no open‑source alternative reaches the same maturity level. The essential point is to make the choice consciously, aware of the technical, legal, and financial implications, and, if needed, to rely on appropriate technical support rather than on habit or fashion.
