A modern cybernetic potentiostat plays a significant role in realizing various electrochemical measurements. This technology report describes a general-purpose, scalable, handheld (10 cm[superscript 2]), yet affordable hardware-software framework for a potentiostat, galvanostat, and electrochemical impedance spectrometer with high capabilities:(1) cyclic voltammetry, square-wave voltammetry, and (potential-step)chronoamperometry as potentiostatic measurements conjugated with iR compensation and rotating-disk electrode apparatus in a wide range of current and voltage (pA to 0.1 A and ±12 V);(2) chronopotentiometry (with an arbitrary current) as a galvanostatic measurement (e.g., Karl Fischer titration); and (3) electrochemical impedance spectroscopy with a bandwidth of 0.1-1 MHz. Two additional devices derived from the framework were also demonstrated for fast potential scanning (up to 100 kV/s) and simple assembling, respectively. The presented framework provides rich teaching materials for chemistry, technology, engineering, and mathematics (e.g., STEM) education.