BP Fluor 405 DBCO is a blue fluorescent dye frequently used in multicolor applications, such as flow cytometry and super-resolution microscopy with STORM. Its excitation is optimal for the 407 nm krypton laser line or 408 nm violet laser diode. BP Fluor 405 DBCO reacts with azides through a copper-free click chemistry reaction to form a stable triazole, eliminating the need for a Cu catalyst or elevated temperatures. In applications where copper presence is a concern, BP Fluor 405 DBCO serves as an ideal alternative to copper-requiring fluorescent alkynes.