PIXresizer is a refreshingly simple photo optimization tool.
In fact, PIXresizer is the perfect app if you want to make very simple changes to your photos before posting, viewing or sending them online. For example, you can use the app to change the photo size (to presets or custom), alter the file format (BMP, GIF, JPEG, PNG, and TIFF) and optimize for emailing and posting.
PIXresizer isn't very flashy, and apart from these functions - and a few other options you can enable, such as saving EXIF data - there's not much more you can use it for. That said, it's free and does its job very well, so if you often need to change the dimensions of your photos, it's a very handy tool to have lying around.
PIXresizer allows you to work with single files or in batches of folders. The two options are under separate tabs, and you'll be able to see a preview if you use the multiple files option.
Quick, simple and does exactly what it says on the tin, PIXresizer is an excellent tool.