The Advanced Scientific Data Format (ASDF) is a next-generation interchange format for scientific data. This package contains the Python implementation of the ASDF Standard. The ASDF format has the following features: - A hierarchical, human-readable metadata format (implemented using YAML) - Numerical arrays are stored as binary data blocks which can be memory mapped. Data blocks can optionally be compressed. - The structure of the data can be automatically validated using schemas (implemented using JSON Schema) - Native Python data types (numerical types, strings, dicts, lists) are serialized automatically - ASDF can be extended to serialize custom data types