GraphicsMagick vs Kraken.io: What are the differences?
Developers describe GraphicsMagick as "The swiss army knife of image processing". GraphicsMagick is the swiss army knife of image processing. Comprised of 267K physical lines (according to David A. Wheeler's SLOCCount) of source code in the base package (or 1,225K including 3rd party libraries) it provides a robust and efficient collection of tools and libraries which support reading, writing, and manipulating an image in over 88 major formats including important formats like DPX, GIF, JPEG, JPEG-2000, PNG, PDF, PNM, and TIFF. On the other hand, Kraken.io is detailed as "Image optimization and compression API". Kraken supports JPEG, PNG and GIF files. You can optimize your images in two ways - by providing an URL of the image you want to optimize or by uploading an image file directly to Kraken API.
GraphicsMagick and Kraken.io belong to "Image Processing and Management" category of the tech stack.