Methods, apparatus, and articles of manufacture to encode auxiliary data into text data and methods, apparatus, and articles of manufacture to obtain encoded data from text data are disclosed. An example method includes assigning encoded data units to respective ones of a plurality of groups, the encoded data units including text data, identifying a symbol present in a first one of the encoded data units assigned to a first one of the groups, and outputting auxiliary data embedded in the encoded data units based on the symbol and based on the one of the groups of the first one of the encoded data units.