Promo Instant Image Resizer - Automatically optimize images for web & social media (free!)
Landscape by Sprout Social - An interactive tool for social media image resizing
Responsive Image Breakpoint Generator - Turn one image into the ideal set of per-device images
OgHero - Generate social share images for your blogs automagically
Placid - Use Placid to auto-generate images, videos & PDFs from reusable templates
Bold - Ultra-fast anonymous publishing platform.