Ingramer is a pretty cool tool that allows you to search hashtags based on keywords. Not only that, it also suggests you the combination that guarantees the best engagement and reach. When searching for a keyword, it shows you a number of hashtags in three categories - frequent, average, and rare. You can use a combination suggested by them that maximizes your post's reach. Moreover, you can simply check the box beside the hashtag you want to select and collect the hashtags until it reaches a total of 30 (which is Instagram's limit of hashtag usage per post). It also gives you a 'copy' button which is a very simple yet a very helpful feature. I have been using it for a few months now and it really makes my work of hashtag marketing easy.