digiKam - Professional Photo Management with the Power of Open Source
TeeSpring - Create & sell t-shirts you can be proud of
XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Zazzle - A wide determination of items in addition to simple-to-use plan apparatuses is Zazzle’s primary attractions.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Teemill - Teemill is a platform that lets you build your own online store and sell t-shirt designs online.