Trigraphy - Photo editing app that allows you to make mosaic/abstract looking art.
Bootstrap 4 Cheat Sheet - An interactive Bootstrap 4 cheat sheet
GIF Brewery by Gfycat - Create stunning GIFs from videos & screen recording for free
Bootstrap Zero - Open-source, free Bootstrap templates collection.
WidsMob Montage - Make stunning mosaic photos or montage shape with tiles, which supports both JPEG and PNG files.
HackerThemes - Bootstrap 4 themes and tools for web developers