Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
Filecamp - Digital Asset Management & Online Proofing tools beautifully integrated, into one secure and cost-effective solution. Manage all your digital marketing assets from your own good-looking, easy-to-use spot in the cloud. Unlimited users in all plans!
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Bynder - Bynder is a cloud-based digital asset management solution for marketing professionals looking to simplify how they manage digital content via one central portal.
GIMP - GIMP is a multiplatform photo manipulation tool.
Connecter - Connecter is a 3d asset manager. It's like Adobe Bridge, but for 3d assets instead of pictures.