Ask HN: How do I get started writing a personal bill pay service?

I've done some research to see how to create a bill pay service, but I can't seem to find the right answers. I understand that there are a number of challenges writing this (security, authentication, accessibility, etc.) but the broader vision is to be able to create a service that can help me help my parents manage their online profile and pay their bills. My first thought is to try to create a simple bill pay service for myself to see if I can get a crude POC going. Essentially, I would like to be able to aggregate a number of utilities, online services, etc where a manager can help another person pay for their bills, rather than logging onto 10 different sites to facilitate this. What resources can I consult to build a simple bill pay service? Thanks!