Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.
Ralpha Image Resizer - High-speed image batch conversion tool