You can get hashtag suggestions for your Instagram photos right inside Hootsuite's publishing field, for their web-to-Instagram scheduling solution.
JUST ADDED: The RiteTag extension's hashtags for image solution shown in the video below also works with all web to Instagram direct publishing and scheduling solutions, including Hootsuite's - and all the others, too! Just follow the instructions for desktop-to-phone Instagram scheduling in the video for use in direct Instagram desktop upload solutions.
The quick video below shows using the RiteTag Pro extension with both Hootsuite and Buffer. It works with all social media publishing tools.
2) Start a new post in Hootsuite with your image caption and upload your image
3) Right click the image and select "Get Hashtag Suggestions"
4) Click the Copy button to copy all hashtags to your clipboard
5) Paste the hashtags to your post, preferably two lines below the caption (not shown)
You can also right-click images in any web page for the Get Hashtag Suggestions solution, even if you didn't upload the image to a Hootsuite, Buffer, Tailwind, Later, Onlypult or other publishing composer. Also, there's a button beside search, on the left side on the RiteTag Hashtag Bar, for getting hashtags for any image in your computer: the up arrow button.
Everything above is for RiteTag X Hootsuite; RiteBoost does far more than hashtags
Instead of hashtag suggestions only, if you would like a one-step solution for image, author-attribution, auto-hashtagging, auto-emojis and even the option to place your self-branded ad (test, image or video) on URLs in your posts, please see this tutorial on RiteBoost X Hootsuite:
How to use the RiteBoost Hootsuite application