Summary Under the proposed Cloud and AI Development Act (CADA, COM(2026) 502 final — a draft regulation, not yet in force), an "open cloud computing stack" is a secure, resilient and performant end-to-end cloud architecture — spanning on-device edge, connectivity, data and AI tools, and backend and service layers — that the EU would develop to strengthen its technological autonomy. The concept appears as operational objective 2, named in Article 3(2)(b) and detailed in Article 4(2). CADA does not define "open cloud computing stack" as a glossary term in Article 2; the meaning comes from the actions listed in Article 4(2), which combine open-source software, EU-designed processors and accelerators, open-source middleware for common European data spaces, and a catalogue of European open cloud solutions.

Detail

CADA's Cloud and AI Leadership Initiatives aim to reduce strategic dependence on a small number of non-European providers. One pillar is the open cloud computing stack — not a single product, but an integrated set of hardware and software layers.

The legal basis is operational objective 2: named in Article 3(2)(b) ("supporting the development and deployment of cloud computing stacks supporting the Union's technological autonomy") and detailed in Article 4(2).

Core components (Article 4(2)(a))

Article 4(2)(a) provides for developing and piloting "secure, resilient and performant open cloud computing stacks covering on-device edge, connectivity, data and AI tools, backend and service layers for strategic sectors." In practical terms, the stack would span:

  • On-device edge — compute close to the data source.
  • Connectivity — the network layer linking edge, data centres and users.
  • Data — storage and data-management layers.
  • AI tools — integrated AI capabilities.
  • Backend and service layers — core compute and application services.

The label "open" reflects the recitals' emphasis on open standards, open specifications and open source, supporting interoperability and reducing lock-in.

Hardware and software designed in the Union (Article 4(2)(b))

Article 4(2)(b) covers developing "AI-optimised servers and baseline software based on processors, accelerators and quantum accelerators designed and manufactured in the Union, alongside next-generation ultra-high density and long-term data storage." The aim is to anchor the physical supply chain of cloud infrastructure within the Union. (The recitals note this should connect with the semiconductor initiative referenced as the future Chips Act 2.0; that reference is recital context and the instrument is not yet adopted.)

Open-source middleware and foundations (Article 4(2)(c)–(d))

Article 4(2)(c) covers boosting data availability for AI "via open-source middleware platforms underpinning common European data spaces." Article 4(2)(d) covers fostering "the creation of open-source software foundations supporting open-source components." Recital context adds that this includes governance and coordination mechanisms and the pooling of resources.

The European catalogue (Article 4(2)(e))

Article 4(2)(e) would establish "a catalogue of European open cloud computing solutions developed under points (a) to (d)." The recitals describe the wider intent — federating with existing public- and private-sector catalogues and acting as a one-stop-shop for open-source resources in the Union — but the operative obligation to create the catalogue sits in Article 4(2)(e).

Strategic context

The stack is explicitly tied to the Union's technological autonomy (Article 3(2)(b)). It maps to Grand Challenge 2 (Cloud stacks) in Annex I, which is about building "end-to-end hardware and software cloud stacks, including AI tools, infrastructure, services and management layers to bridge the Union's critical capacity gaps."

What this means for you

For CTOs, architects and SMEs, the open-stack agenda signals where European support and procurement preference may flow. Most of Article 4(2) creates objectives for the Initiatives rather than direct duties on private firms.

  • Procurement and vendor selection. Open, interoperable stacks built on EU-designed hardware and open-source components are likely to be favoured in public procurement. CADA's separate procurement provisions (for example the public procurement of innovation measures referred to in Article 33) and the Union assurance levels in the proposal's sovereignty title govern how that preference operates in practice.
  • Interoperability and multi-cloud. The emphasis on open standards and open-source middleware makes portable, multi-cloud architectures more viable; prioritising open specifications reduces lock-in.
  • Open-source contributions. The push for open-source software foundations (Article 4(2)(d)) is an opening for SMEs to contribute to and draw from a shared European ecosystem.
  • Hardware supply chain. The drive for EU-designed processors and accelerators (Article 4(2)(b)) is a long-term signal; integration will be gradual and market-driven.
  • The European catalogue. Listing in the catalogue of European open cloud solutions (Article 4(2)(e)) could raise visibility with public-sector buyers.

Common misconceptions

"'Open cloud stack' means open-source software only." It spans the whole architecture — hardware, connectivity, data, AI tools and services — designed to be open and interoperable end to end (Article 4(2)(a)–(b)), not just open-source code.

"This bans non-EU cloud providers." It does not. Article 4(2) supports building European alternatives; it does not prohibit non-EU providers. CADA's sovereignty framework recognises providers across graded assurance levels rather than banning them.

"SMEs cannot compete with hyperscalers here." The open-standards and open-source-foundation approach (Article 4(2)(d)) lowers barriers and lets SMEs specialise in specific layers.

"Technological autonomy means isolation." Autonomy here means credible European alternatives and reduced critical dependencies, not withdrawal from global markets.

Related

This is general information about a draft EU regulation, not legal advice.