Soybean variety XB15J13

A novel soybean variety, designated XB15J13 is provided. Also provided are the seeds of soybean variety XB15J13, cells from soybean variety XB15J13, plants of soybean XB15J13, and plant parts of soybean variety XB15J13. Methods provided include producing a soybean plant by crossing soybean variety XB15J13 with another soybean plant, methods for introgressing a transgenic trait, a mutant trait, and/or a native trait into soybean variety XB15J13, methods for producing other soybean varieties or plant parts derived from soybean variety XB15J13, and methods of characterizing soybean variety XB15J13. Soybean seed, cells, plants, germplasm, breeding lines, varieties, and plant parts produced by these methods and/or derived from soybean variety XB15J13 are further provided.