Autotracer.org - Free online image vectorizer
Bulk Resize Photos - Resize large photos in bulk
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.
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.
RasterVect - Professional raster to vector conversion program (vectorizer).
GIF Resizer - Create animated GIFs and resize GIFs too big to tweet!