FastStone Image Viewer, IrfanView, Microsoft Photos, digiKam, ACDSee Photo Studio, XnView, Shotwell, gThumb, Zoner Photo Studio X, Movavi Photo Manager, Excire Search, Tonfotos, Pictomio, FotoAlbum, jBrout, JPEGView, qimgv, GPicSync, Photos to Albums, Jetphoto, Photodali, PhotoTime, ABCFastDirectory are some alternatives to Phototheca.