Penny

Penny

Industry: Fintech / WealthTech
Region: Sweden

Overview

Swedish company Greenmerc wanted to make wealth management accessible to everyday Europeans. The result is Penny, an automated investment app that bridges regular savings and professional investing. Users link their bank accounts, set financial targets, and Penny monitors their finances in real-time — automatically investing leftover funds at month’s end without any manual effort. Build NYC Tech helped bring this vision to life through staff augmentation.

Challenges

  • SDK incompatibility: Greenmerc used Tink (a Visa subsidiary) for open banking connectivity, but Tink’s SDK was built in native Swift and Kotlin. Penny was built on React Native, creating an immediate compatibility conflict.
  • Geographical barriers: The app required BankID for login, Sweden’s standard digital verification system. With the development team based in Bangladesh, there was no physical access to Swedish banking infrastructure, making testing extremely difficult.
  • Unstable APIs: The investment engine, Cairo, was still in active development with frequently changing API requirements, threatening the overall project timeline.
  • Localization requirements: The app needed seamless, rock-solid support for both English and Swedish languages from day one.

Solutions

  • Custom React Native bridge: Build NYC Tech’s mobile engineer wrote a custom native bridge, allowing the React Native framework to communicate directly and flawlessly with the native Tink SDK.
  • Mock environment simulation: The team architected a sophisticated mock environment simulating Swedish bank accounts and login flows, enabling full remote testing of complex transaction workflows from Bangladesh.
  • Agile integration strategy: A flexible backend architecture was implemented to gracefully absorb Cairo’s frequent API changes without disrupting core app functionality.
  • Dynamic localization engine: A scalable file mapping system was built to allow instant, reliable language switching between English and Swedish throughout the entire app experience.