Spack is the de facto standard for software delivery across the HPC ecosystem, giving teams a single tool to manage software complexity from laptops to leadership-class systems. Originally developed under the NNSA Advanced Simulation and Computing program and adopted as the primary integration tool during the DOE Exascale Computing Project, Spack is now a founding project of the High Performance Software Foundation (HPSF) and a foundational component of the CASS ecosystem.
- Scale: A community-maintained repository of more than 8,600 package recipes, backed by cloud-hosted build and test infrastructure that runs over 100,000 builds per week across Amazon Web Services and the University of Oregon’s Frank cluster.
- A 1.0 milestone: Spack reached its 1.0 release in FY2025, with follow-on releases addressing facility-specific challenges such as compiler mixing and expanded binary compatibility.
- The foundation for E4S: Spack is the packaging technology E4S is built on.
PESO’s role in Spack. NNSA supports the foundational development of Spack’s core technology; PESO’s investment is distinct, directing Spack’s capabilities toward ASCR-specific integration challenges, open-science facility deployment, and the interoperability the CASS ecosystem depends on. PESO provides the stewardship infrastructure that turns contributions from thousands of DOE scientists into a reliable, tested software stack, and works closely with CASS software teams to ensure the features they need are supported in Spack. Todd Gamblin (Lawrence Livermore National Laboratory) leads Spack under PESO.
Learn more, browse packages, or get involved at spack.io.