In this start-up company, I was involved right from requirement gathering, engineering and deployment. As a small team, we built and experimented a lot of products - real CRM, messaging CRM using XMPP, SoLoMO app, Migration app etc.
My biggest accomplishment is building a migration app, which stores data in a secure format for future use, something like Internet Archive in current times.
The other biggest accomplishment is learning how to design and build API for mobile App. Apart from this, I also had the advantage of learning to code in Java and Objective C and contribute to the app in Android and iOS.