During my undergraduate studies I collaborated with my fellow classmate and developed an Android application using Android Studio. We developed a simple application to eliminate the middle-man(broker) between a buyer and seller in the commodity (raw crops, vegetables, etc.) market.
Application is registered in via sim number (generating OTP every time user a needs to register to the application). Generating OTP and storing phone numbers as unique keys (id) was achieved using FireBase.
A user can use the application both ways, he/she can either log in and select "Buyer" option to proceed as a buyer or he/she can log in and select "Seller" option to proceed as a seller.
Selecting "Buyer" option allows us to navigate the app as a Buyer, we can see the feed which includes all the commodities posted by Sellers. We can further sort the list of postings by using filters(e.g., location, name of seller, type of commodity etc.). We can see the information of seller and make contact with him to further discuss the negotiations. (We won't need a middle man, we can buy commodities directly from seller at cheaper price).
Selecting "Seller" option allows us to make a post of our goods. Once we enter the details about our goods and hit the submit button, our post will be generated in feed on Buyer's section. (Some buyer will then make contact with us regarding our post, we can directly sell our commodity to buyer without any middle man)