Modern cheminformatics tools offer a multitude of ways of storing chemical information for single molecules or small collections. We identified a need to access molecules or conformer ensembles from large collections without the necessity to create a full-fledged database. A binary molecule and conformer serialization strategy was implemented through a disk-based dictionarylike structure of MessagePack-serialized data that we refer to as uKV file (see the Supporting Information for details). This form of storage offers the flexibility of storing molli objects in large random-access files, with optimized read/write performance.