Denis – Python, React, AWS

One of the largest platforms enabling pay-as-you-go distribution of solar and other essential products in emerging markets, offering technology for remote device activation, payment tracking, and customer management.

• Spearheaded the frontend rewrite from Knockout to React;
• Designed and led the migration from self-hosted Basic Auth to AWS Cognito, enabling secure MFA and strengthening the platform’s authentication model;
• Re-architected the company's CRM to run on Docker via AWS ECS, improving scalability and significantly reducing infrastructure costs;
• Integrated multiple Mobile Money providers and banking partners;
• Built the underwriting engine to enable data-driven device loan approvals for customers with higher repayment likelihood;
• Architected and implemented a fully decoupled SMS infrastructure using serverless technologies;
• Developed a two-way conversation framework used across new services (USSD, bidirectional SMS, WhatsApp) to power consistent automated customer interactions;
• Implemented API caching mechanisms to reduce load and improve performance across high-traffic endpoints;
• Built CI/CD pipelines for the underwriting engine to streamline deployments and ensure reliable delivery;
• Led the upgrade of a 20 TB PostgreSQL database from Postgres 16 to 17.

A cashless fare-collection platform designed to help the African transport industry securely and efficiently manage digital payments while eliminating the risks and complexities of handling physical cash.

• Designed and implemented the frontend and backend architecture;
• Integrated the frontend with Clerk authentication;
• Developed wallet functionality enabling users to send, receive, and disburse funds;
• Set up a CI/CD pipeline to deploy the backend to AWS and the frontend to Vercel;
• Introduced Zustand for efficient state management on the frontend.

A web application that streamlines medical appointment scheduling in the sub-Saharan region, enabling staff to manage appointments and reminders, while allowing patients to book visits without calling.

• Designed and implemented the frontend and backend architecture;
• Built and automated the deployment pipeline to AWS using GitHub Actions;
• Developed integration tests that validate changes in the staging environment before production deployment.

A B2B platform that connects suppliers with bulk buyers, enabling group purchases to access lower MOQ-based pricing and facilitating the logistics.

• Built the frontend application from scratch and integrated it with existing backend APIs for full end-to-end functionality;
• Implemented unit test coverage and introduced test-driven development, improving code quality and maintainability.