Abstract: Techniques and systems for decoding optical codes using symbol-based algorithms are described. In one example, a method includes acquiring a signal representative of light reflected from an optical code comprising one or more symbols of a finite set of symbols and applying a decoding model to the signal. The decoding model may relate measured signals to the finite set of symbols, such that each of the symbols of the finite set of symbols are associated with a respective encoded character of a finite set of encoded characters. The method may also include determining, by a processor, a sequence of one or more of the encoded characters based on the application of the decoding model to the signal. In this manner, the optical code may be decoded by directly fitting an acquired signal from the optical code to possible symbols within the optical code and the associated encoded characters.