Step-Counter Donation App

I need a cross-platform mobile app that quietly counts every step I take on both iOS and Android. Once the daily or user-defined step goal is hit, the app should trigger a seamless donation flow so I can instantly give to a charity I select.

The overall look must feel corporate and professional—clean lines, muted colours, intuitive layout—so it can sit comfortably in a business context and still be easy for everyday users.

Core scope
• Accurate step tracking that runs reliably in the background.
• A configurable target that, when reached, opens or auto-initiates the donation screen (API or web checkout—whichever you recommend).
• Extra features I definitely want included:
– Kalori hesaplama (calorie burn estimation).
– Arkadaşlarla yarışma (friendly competitions with invite codes or contact list).
– İlerlemeyi paylaşma (one-tap sharing of progress to social platforms or messaging apps).

Please build for both operating systems from the same codebase if possible and provide the full source, installation packages, and a brief hand-off guide so I can maintain future text or charity changes internally. If you already have experience integrating payment gateways or charity APIs let me know; that will be a strong plus.