AtoM (Access to Memory) is a mature, open-source web application for archival description and access, developed by Artefactual Systems. In production, it manages hierarchical archival descriptions (fonds, series, files, items), authority records, repositories, digital objects, and accessions. It supports multiple archival standards (EAD, EAC, MODS, METS, Dublin Core) and provides multilingual, multi-repository archival description. The application is built on PHP 7/8 with a Symfony 1.x core, Propel ORM for persistence, and Elasticsearch for search indexing, with MySQL/MariaDB as the primary datastore and Gearman for background job processing.