Smallpdf - PDF document management and conversion suite
ImBatch - ImBatch is a batch image processor with a nice graphical user interface.
iLovePDF - Free online PDF tool set
DVDVideoSoft Image Convert and Resize - Free Image Convert and Resize is a compact yet powerful program for batch mode image processing.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Ralpha Image Resizer - High-speed image batch conversion tool