InstagramDownload is a free and portable software that will allow us to download any picture of any Instagram user there is.
The pictures are not downloaded into your PC, they are,instead, placed into a little .txt file in the folder where the software is. The .txt file will contain the original links of the images, allowing you to access to them via a browser, or bulk download them all with a download manager.
In any way, is a very awesome and powerful engine that will make very easy to keep a backup of our images in a single file.
Link | InstagramDownload