HORIZON-CL4-2026-04-HUMAN-02: Web 4.0 architectural framework and Open Internet Stack applications for virtual worlds (RIA)

Expected Outcome:

Common expected outcome

Stimulate the emergence at European and global scale of Web 4.0 (such as standards, protocols, components and a framework for their interaction) and virtual worlds solutions.

Expected outcome for the “Architectural Framework” area

• An emerging Web 4.0 architectural framework made of cross-platforms, interoperable, trustable, safe and secure building blocks that rely on Open Source software
• A structured and agile eco-system of talented contributors driving the creation and evolution of commons based on Open Source software, open standards and open hardware and designs.

Expected outcome for the “Applications” area

• Open source and made in Europe, supporting trust and sovereignty, and delivering credible alternative choices for citizens, governments and companies including start-ups and SMEs.
• Interoperable, standards-based, decentralised solutions exploiting extended reality technologies.
• Compliant-by-design with EU rules and regulations. Paced for easy deployment by the rich European eco-systems of providers, integrators and verticals.

For both areas the outcome will bring synergies with actions under Virtual worlds, Open Internet Stack, 3C, as well as with other like-minded actions in Europe e.g. at Member States level and outside

Scope:

Proposals should address one of the following areas and should clearly identify the area addressed.

1/ “Architectural Framework” area

Develop a human-centric Web 4.0 architectural framework encompassing interoperable layers from open hardware, web, AI agents, up to immersive and decentralised applications, utilizing cross-platform digital commons developed by European innovators (SMEs, start-ups, academia). Proposals should demonstrate immersive multi-modal user interaction and should enhance trust, privacy, portability, and advanced identity management, facilitating deployment of the EU Wallet while optimizing the balance between decentralization, security, and energy efficiency with verifiable metrics.

2/ “Applications” area

Proposals will cover the one or more of the following technologies:

• Alternative decentralised applications and services such as synchronous and asynchronous messaging, videoconferencing, collaboration and groupware or social media that can be exploited through Virtual Worlds technologies, including immersion and interaction.
• App-stores (incl. web-based) adapted for Virtual Worlds
• Shared, robust and trustworthy cross-technology Virtual Worlds for user and attribute management

Proposals will have to demonstrate (1) technical maturity in terms of scalability, resiliency, alignment with standards (2) critical mass of communities actively supporting the development (3) evidence of interest from users and deployers of the solutions.

Cross-cutting requirements for both areas:

Applicants should define the mechanisms for maturing building blocks e.g. security and accessibility audits, packaging of the software for easy deployment, localisation of the software in EU languages, documentation of best practices and advising on licensing.

Applicants should detail the path to growth for building blocks e.g. by defining a clear standardisation strategy, actively animating communities, creating momentum among like-minded efforts, defining how projects will gain critical mass and what services will be provided for reaching such stage, and providing a coherent picture of the portfolio for adopters

Applicants should create the conditions for successful collaboration and synergies with other European initiatives such as the Virtual Worlds/Web 4.0, 3C and Open Internet Stack initiatives as well as with like-minded funding efforts at national, European levels and beyond Europe such as Digital Commons initiatives.

Applicants should demonstrate their experience and understanding of Open Source communities and their expertise covering the full Open Source life cycle through proven track record including years of experience.

Beneficiaries that intend to transfer ownership or grant an exclusive licence must formally notify the granting authority (i.e. DG-CNECT and HaDEA) before the intended transfer or licensing takes place and the granting authority may up to four years after the end of the action object to a transfer of ownership or the exclusive licensing of results.

Financial support to third parties

If applicants opt for financial support to third parties, then they should target calls towards European Open Source communities – SMEs, research institutes and individual researchers and developers – with solid experience with development of solutions in line with EU rules and values. Applicants should provide the programme logic for the third-party projects, managing the projects lifecycle, and provide the necessary technical and non-technical support: these tasks cannot be implemented using the budget earmarked for the financial support to third parties.