ROOT

ROOT, developed and maintained by the ROOT Team at CERN with contributors from Fermilab, GSI, Princeton, and UC San Diego, is a modular scientific software framework for processing and analyzing enormous datasets — with over 2 exabytes currently stored in ROOT files, and famously used to discover the Higgs boson. It handles petabyte-scale data analysis, includes a C++ interpreter for rapid prototyping, provides Python interfaces with dynamic bindings, and integrates with Jupyter notebooks for interactive analysis. Open development invites community contributions, and the project is actively maintained with recent releases (6.40.02, June 2026) and ongoing hackathons and training courses. Completely free and open source. Good fit for a physicist or scientific researcher working with massive datasets who needs proven, petabyte-scale analysis infrastructure rather than general-purpose data tools not built for that scale.