Intelli Hash is a powerful app to get hashtag suggestions from images. It uses powerful image recognition API from Imagga. The app is open source.
Using the Intelli Hash app, you can not only get suggestions for hashtags but also copy and share these hashtags on other media.
Tagsdock 3.0 is a keyboard for Instagram.
RiteTag 2.0 suggests relevant, engaging hashtags from the images and text on your devices so you don't have to guess anymore.