A free program for Android, by Craftorogue.

Reposter is an application that allows you to repost photos and videos from your gallery on Instagram, Facebook, Twitter, Snapchat, etc. 

It is an application that has a simple and intuitive interface. The first step is to select the photo or video that you want to repost on Instagram, Facebook, Twitter, Snapchat, etc. The second step is to select the account that you want to repost on. After that, you will have a window in which you will be able to write the message that you want to add to the photo or video. You can also add stickers, text, etc. 

You will also have an option to download the photo or video directly to your gallery.