Trigraphy - Photo editing app that allows you to make mosaic/abstract looking art.
AndreaMosaic - With AndreaMosaic you can create your own photographic mosaics made with your own pictures.
Dreamscope - Make and share 'deep dream' images using dozens of supplied styles or your own.
WidsMob Montage - Make stunning mosaic photos or montage shape with tiles, which supports both JPEG and PNG files.
Photomosh - Turn anything into a vaporwave
Mosaic Creator - Mosaic Creator is professional mosaic tool. You can create your own picture mosaic.