CDR Annotation is an antibody numbering and annotation module used to number the variable region (Fv) of antibody sequences, accurately marking the specific locations of the framework region (Framework Region, FWR) and the complementarity determining region (Complementarity Determining Region, CDR). It supports the IMGT, Kabat, Chothia, Martin, AHo and Wolfguy schemes. If multiple sequences are input at once, the amino acid frequency plot in the results can be used to analyze the diversity of the Fv and CDR regions.