A simple tool that will help visualize bounding boxes in darknet/yolo format. The only package needed for this is work is OpenCV
python vis_bbox.py --folder_path path/to/folder --classes path/to/classes.names --save_path folder_to_save/
--folder_path is the path to the folder containing the images and the labels
--classes is the path to the classes.names file
--save_path is the path where the saved images will be stored (will be created automatically if folder does not exist)