Bulk Resize Photos - Resize large photos in bulk
Autotracer.org - Free online image vectorizer
Bulk Image Resizer by RedKetchup - Resize, convert, or compress multiple images quickly. Compress PNG, JPEG, WEBP, or HEIC images in batch. Convert multiple images to the PNG, JPEG, WEBP, HEIC, GIF, ICO, TIFF, or BMP formats.
PNG to SVG Converter - PNG to SVG Converter is a dynamic platform that offers you to convert PNG images to scalable vector graphics without any difficulty.
GIF Resizer - Create animated GIFs and resize GIFs too big to tweet!
RasterVect - Professional raster to vector conversion program (vectorizer).