
This work presents a lightweight multi-factor authentication (MFA) system designed for FinTech users operating under constrained 2G and 3G network conditions common in Nigeria and other emerging markets. The paper evaluates the performance of an optimized Java/Spring and Next.js implementation, focusing on payload reduction, session-token efficiency, and end-to-end authentication latency. Experimental results demonstrate that secure authentication can be achieved with sub-2 KB payloads and low authentication times even under 300 ms latency. This research aims to improve access, trust, and security for users in low-bandwidth environments.