PhotoPenguin App - PhotoPenguin is a completely free batch photo editor with support for cropping, resizing, adding watermarks, and converting photos to other formats. It works on the user's device, using the capabilities of modern browsers.
Online Convert - Convert files like images, video, documents, audio and more to other formats with this free and fast online converter.
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
Pixillion - Easily convert photos and images between file formats in a batch or single file. Compress, rotate, resize, or add text and watermarks to any file. Free download.
Batch Image Resizer - Resize, crop, shrink, flip, exif-rotate, convert, enhance, process multiple pictures and photos with professional software! 120+ Actions, 30+ Image Formats
FileStar - With FileStar you can "do anything with any file".