BLPLook is a QuickLook generator for .blp files, providing a preview of the BLP image in Finder and other applications supporting Quick Look. BLPLook requires macOS 10.5 or later.
BLPView is a thumbnail provider shell extension, allowing Windows to display thumbnails and previews of BLP images. BLPView requires Windows Vista or later.
These utilities only preview BLP images — they do not allow you to convert BLP files to other formats.