Supercomputing and AI systems designed for compute- and data-intensive applications, including large language models and massive simulations, can incorporate tens or hundreds of thousands of compute nodes. At the heart of these massive systems lies the interconnect, the backbone that dictates overall performance, which must seamlessly scale alongside the high-end compute elements for everything to perform well. This is where the EU-funded NET4EXA project comes in, implementing the next generation of European interconnect technology comprising both hardware and software, proven in pilot. Building on the success of BXI, Europe’s production-proven interconnect, NET4EXA is powered by a cohesive consortium of eight partners from industry and academia. The project paves the way for BXI technology to enter the market competitively and cost-effectively, with scientifically validated performance.