CERN Open Data Portal

CERN Open Data Portal

CERN's Open Data Portal serves particle-physics datasets, simulations and analysis examples released by LHC experiments (CMS, ATLAS, ALICE, LHCb and others) via a JSON records API. The terms of use say: "The CERN Open Data Portal is provided free of charge. All metadata and datasets in the CERN Open Data Portal are made available under the terms of the CC0 waiver."

Coverage

Records spanning collision, simulated and derived datasets, software and documentation across LHC experiments; a sampled records query (2026-11-09) reported a doc_count of 82,428 in its own aggregations (a live, not fixed, count). Large data files (ROOT/AOD and similar) are linked, not mirrored. Update cadence: Not stated.

Verdict

Particle-physics collision datasets, simulations and analysis examples released by LHC experiments (CMS, ATLAS, ALICE, LHCb), with a JSON records API, no key. Licensed CC0-1.0 for metadata and datasets: "All metadata and datasets in the CERN Open Data Portal are made available under the terms of the CC0 waiver." WARNING: other content keeps its own terms: "All other content is made available under its applicable license conditions as specified on the relevant web pages. For example, software packages are usually licensed under GNU General Public License (GPL)." Bulk email harvesting is barred: "Bulk downloading of email addresses taken from CERN Open Data Portal is not allowed." Rate limits: Not stated. The large ROOT/AOD-style files behind these records are not mirrored; Signal Lab links only.