How to quickly bring an image to equal sides?

Question

CMS

Good afternoon everyone.
Now you need to upload a large number of pictures to the site, but the template already says so that you need to upload pictures of equal sizes (i.e. so that they are square in fact, i.e. so that all sides are even) what would be on the site everything was displayed without artifacts.
Tell me if there are any tools or processors that can do this with photos?
those. if the photo is 700 by 533, the handler takes the smaller size in width or height and aligns it to the largest (without stretching)

Answer 1

Fast Stone Photo Resizer

Answer 2

Adobe Photoshop can batch process a bunch of files.
Or take JS / PHP (anything is possible, but it's easier with them IMHO) and wool through GD .