The antimicrobial peptide database (APD) has been updated and expanded to version 2 (APD2), now hosting 1,228 entries with diverse activities, including anticancer, antiviral, antifungal, and antibacterial peptides. APD2 introduces new search capabilities, allowing users to search for peptide families, sources, post-translationally modified peptides, and binding targets. Statistical analyses reveal that frequently used amino acid residues vary among different biological sources, such as Ala and Gly in bacterial peptides, Cys and Gly in plant peptides, and Leu, Ala, Gly, and Lys in amphibian peptides. These findings are used to demonstrate database-aided peptide design, where three peptides were designed based on these residue frequencies. One of the designed peptides, GLK-19, showed higher activity against *Escherichia coli* than human LL-37. The update enhances the reliability of statistical analyses and provides a valuable tool for peptide design and research in the field of antimicrobial peptides.The antimicrobial peptide database (APD) has been updated and expanded to version 2 (APD2), now hosting 1,228 entries with diverse activities, including anticancer, antiviral, antifungal, and antibacterial peptides. APD2 introduces new search capabilities, allowing users to search for peptide families, sources, post-translationally modified peptides, and binding targets. Statistical analyses reveal that frequently used amino acid residues vary among different biological sources, such as Ala and Gly in bacterial peptides, Cys and Gly in plant peptides, and Leu, Ala, Gly, and Lys in amphibian peptides. These findings are used to demonstrate database-aided peptide design, where three peptides were designed based on these residue frequencies. One of the designed peptides, GLK-19, showed higher activity against *Escherichia coli* than human LL-37. The update enhances the reliability of statistical analyses and provides a valuable tool for peptide design and research in the field of antimicrobial peptides.