Methods and apparatus, including computer systems and program products, for creating and using documents with machine-readable codes. A computer program receives user data provided for one or more fields in an electronic document, generates input data containing the user data and metadata that provides a self-contained description of the user data, encodes the input data into a machine-readable code, and generates a final representation of the electronic document with a display of the machine-readable code. Upon reading the machine-readable code, the metadata can be used to identify a set of fields in a target system to which to assign the user data. In some embodiments, the metadata and the user data can be transformed and sent to a target system. The use of metadata in this manner enables machine-readable codes to maintain a physical representation of data that facilitates transfer of the data back into an electronic environment.