Really liked the UI , however, i’m more interested in the blueprint calculator.
If you want to have your tool stand out from the rest, one nice feature would be to have a blueprint ranking system - price of the input materials vs price of output materials vs the total volume sold. API exposes market data and its easy to get all existing blueprints (BPOs, BPCs created from BPOs and BPCs such as the trig ones). However, i’m not sure it has an endpoint to retrieve the materials needed for a blueprint. I leave that for you to find out 
Anyway, nice tool. keep it up!