Research in the field of cell-free protein synthesis deals with the synthesis of recombinant proteins in various cell-free systems. In order to analyze proteins, these must first be made available in a functionally active form. The expression of proteins in living cells, i.e. in vivo, is widely used, but does not always yield the desired results, since not every protein can be satisfactorily synthesized in cell cultures. Cell-free protein synthesis thus offers an efficient alternative to the expression of proteins in living cells, whereby the substances found within the cell are used to produce a certain target protein quickly and cost-effectively. The use of eukaryotic cell lysates has the special advantage of allowing the synthesis of proteins with post-translational modifications (PTMs). Particular emphasis is placed on the characterization, modification and functional examination of the cell-free produced antibody formats and membrane proteins. Cell-free systems are used in time-saving, highly parallelized methods to synthesize antibodies and membrane proteins and to immediately integrate these into functional analysis.