Building an API to show related hashtags, popular hashtags, etc?


I want to build a website that basically shows images/pictures from other social networks based on hashtags. In other words, it will connect to other networks like Instagram, Twitter, Pinterest, and display images based on the hashtag that a user searches for in a query search box.

Problem is apparently there has not been an API created for this purpose yet. An API that allows people to see hashtags related to the hashtag in a search query, top influencers for a queried hashtag, most popular related hashtags to the queried hashtag. Basically, I need multiple APIs that displays hashtags through different criteria.

Would it be hard to make a custom API or app? I know there are some 3rd party tools that make you pay for services that offers in-depth statistics about hashtags that you want to look up. I want to offer a service that is open, flexible, and free…though who knows if I will offer a fee. I’m not sure if Instagram or Pinterest have an API either for customized hashtags displays.