Accounting Software

My business is currently using Tally, Khatabook, Bizanalyst and Vyapaar App for its accounting needs, that are rental based apps. Now i want to build software like Vyapaarapp. To that end, I am looking for someone to develop a custom software application specifically tailored to my needs to help us with our accounting processes, Income tax filing and GST Filing process. The software must be able to import data from Excel spreadsheets and it should be mobile based. Additionally, it must be compatible with Tally, so that our data is accurately and automatically transferred as needed. I am open to other data import capability options and features, so please share your ideas.