Open source provides a particularly suitable foundation for this. Open source code, together with extensive rights of use and further development, enhance transparency, control and flexibility. Our article ‘Digital Sovereignty and the Role of Open Source’.

Translating digital sovereignty into requirements

Terms such as openness, independence or digital sovereignty must be defined in a concrete and verifiable manner in tender documents. This may include, for example:

• open and documented interfaces,
• portable data formats and comprehensive export options,
• rights of use and further development,
• the ability to switch providers, support or service providers.

Open source creates important conditions for interoperability, independent further development and the ability to switch between different providers. The tender must clearly set out why these characteristics are necessary for the specific contract.

Our article on the European Technological Sovereignty Package.

Can open source be specifically requested in tenders?

A report by the Scientific Services of the German Bundestag on the procurement of open-source software concludes that: Restricting the subject matter of the contract to open-source software may be permissible under public procurement law if it is justified by objective requirements specific to the contract in question. These may include, for example, IT security, interoperability, independent further development or the avoidance of vendor lock-in.

The requirements must be based on actual needs, be proportionate and be documented in a transparent manner. By contrast, a purely political preference is not sufficient for contracts above the EU thresholds.

As a rule, the possibility of equivalent solutions must also be taken into account. Whether a solution is equivalent depends on the requirements set out in the specifications. In addition to the scope of functionality, this may also include data portability, rights of use, open interfaces, options for switching and long-term freedom of design.

Considering vendor lock-in and cost-effectiveness

The consequences of a procurement decision often only become apparent during maintenance, upgrades or migration. If only the original manufacturer holds the necessary rights or proprietary knowledge, competition for subsequent contracts may be significantly restricted.

Our article explains how vendor lock-in arises and how open source can help reduce dependencies: ‘Avoid vendor lock-in: Open source as risk minimisation’.

The cost-effectiveness of software should also be considered over its entire lifecycle. In addition to licence and implementation costs, this includes operation, maintenance, customisation, support, price changes and a potential migration.

Open source offers the opportunity to make costs and services more transparent, to maintain competition between service providers and to safeguard investments in the long term. Which solution is the most cost-effective in a specific case must be assessed on the basis of the total costs and actual requirements.

Open source as the basis of sovereign infrastructure

An open-source licence creates essential conditions for transparency, verifiability and freedom of design. It realises its full potential when combined with an open and sustainably operable technical infrastructure.

When evaluating a solution, therefore, other characteristics should be considered alongside the licence:

• a comprehensible and maintainable architecture,
• open standards and documented interfaces,
• reliable security updates,
• professional support services,
• flexible operating models,
• ongoing development,
• the portability of data, operations and support.

Open source enables public sector contracting authorities to independently verify key technical characteristics – or have them verified – and to retain long-term influence over the systems deployed. It thus provides a strong foundation for sovereign, resilient and future-proof public IT.

Embedding digital sovereignty in the specifications

Public procurement often shapes digital structures over many years. The requirements set out help determine how securely and flexibly systems can be further developed, whether data remains permanently accessible, and what choices exist between providers and operating models.

Open source offers far more than just an alternative licensing model. It enhances transparency, competition, interoperability and the independent further development of digital infrastructure. In this way, open source creates key prerequisites for sovereign and sustainable public IT.

It is crucial to translate this potential into concrete, proportionate and transparently documented requirements. In this way, digital sovereignty becomes not just a political objective, but a verifiable component of procurement.