Here’s a case study on a bill payments app I had worked on a couple months ago.
Project: YuPay
Client: MyFatoora
Deliverables: iOS, Android & Windows App design
About Project: YuPay is a bill payments app used to pay logistics, broadband and electricity bills for the consumers in UAE.
Tools Used: Pen & Paper, Trello, Adobe Photoshop, Sketch App, Zeplin.
Credits: iOS & Android design by Paresh Khatri, Windows design by Darshan Gajara, project managed by Indiez.
A native typeface for the best performance,
iOS: Helvetica Neue
Android: Roboto
Windows: Segoe UI
Design For iOS
iOS users are addicted to retina-rich pixels and they’re quite sophisticated about it.
Design For Android
Android users are those hustlers who would never be satisfied by just what you offer. They demand more.
Design For Windows
Microsoft has certainly kept a sharp eye on design with their new Universal Windows Platform (UWP). It’s rich and elegant and focuses on usability.
YuPay app would be soon made available on their respective stores. I shall update the links here once it’s live.
You may check the complete presentation on Behance and leave all sorts of feedback. Yup, I’m listening 🙂
Darshan Gajara 
For India Paytm is the best, as it gives lots of option and cashback.
Sure Rahul, Paytm is a good application for Indian payments, but I would prefer Freecharge over it. Their UX is pretty smooth.