SysWoe

Initial release: 2020

SysWoe (System of Wɔɛ) offers a local proximity exchange system that networks individuals, sellers and service providers residing in the same geographical area, using WOE as a digital currency of exchange. SysWoe is still a work in progress, and many features are yet to be added: Merchant accounts and an in-app digital marketplace for retailers. SysWoe is part of the HubCity Smart City initiative.

🧰 Tech stack

• Languages: Dart
• Frameworks: Flutter
• Backend: NestJS REST API with JWT auth
• Database: Hive, PostgreSQL (with TypeORM)
• Tools/Software: Android Studio/Docker/Figma
• Architecture Pattern: Clean Architecture + MVVM

🖼️ Screenshots

⚙️ Technical challenges

Challenge	Solution
Real-Time balance update	In order to reflect balance updates, I implemented websockets, and triggers on the database. Whenever a transaction is made, the parties are securely notified, with a metadata payload.
Prevent duplicate transactions client-side in the send money flow	When the user initiates a payment flow, a unique id is generated and used as a token for that transaction. This allows the backend to know if a request is a duplicate or not.
Avoid duplicate transactions server-side	Use of Query runner to run database transactions to guarantee ACID properties that are crucial here. Simultaneous transactions are treated separately in a queue.

👨‍💻 Project duration and role

SysWoe has had many versions over the years. The initial version was released in a week and comprised basic currency (Wɔɛ) transfers between users. As the CTO of HubCity, I was both the lead developer and product owner of SysWoe, focusing on the entire project pipeline, from UI/UX design to modeling, backend and mobile app development.

📲 Experience the app

🌍 Real world pictures

User onboarding of the SysWoe app