E
Ernest Yoyowah
Lead Frontend Engineer · MTN Ghana

Software Engineer
Full-Stack · Payments
& Native macOS Tools

Working at MTN Ghana on payment flows, mobile platforms, and backend services. Also building native macOS and cross-platform mobile tools under Ernest Keyz Studios.

ReactTypeScriptNode.jsGolangSwift
View projectsEngineering experience
Based in Accra, Ghana
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Engineering Experience

Systems Built, Infrastructure Owned

Not just a job history — a record of systems engineered, infrastructure scaled, and financial flows secured.

Full-time

MTN Ghana

Jul 2023 — PresentAccra, Ghana
CurrentMTN Pay & Self Service Portal

Lead Frontend Engineer

Mar 2025 — Present

Leading frontend on MTN Pay and the Self Service Portal — MTN's payment gateway and self-service platform for broadband, bundles, SIM, and eSIM management.

Built secure payment flows for Mobile Money, PCI DSS-compliant Mastercard checkout, and airtime across broadband and digital services
Engineered end-to-end transaction flows — MSISDN input, OTP verification, async status handling — with resilient retry and duplicate-submission logic
Implemented SIM swap validation and Ghana Card (NIA) identity verification for high-risk operations
Enforced OWASP-aligned security across all flows: input sanitisation, secure token handling, no hardcoded secrets, safe redirects
Collaborated with DevSecOps on Fortify scans; trusted as go-to engineer for critical production escalations
ReactTypeScriptNode.jsGolang
MTN PayMTN SSPAirtime & Bundle PaymentsMastercardPCI DSS
MTN Pulse Team

Software Engineer

Jul 2023 — Feb 2025

Software engineer on the MTN Pulse team — MTN's youth platform within the MyMTN app, serving 100,000+ active users.

Identified 15+ codebase inefficiencies and executed a migration plan that reduced technical debt by 40%
Built a Golang API proxy serving realtime streaming analytics across multiple MTN apps
Built backend services in Node.js and MongoDB; contributed payment integration flows (Mobile Money, airtime) to the Pulse app
Contributed to Agile delivery — sprint planning, feature demos, and iterative feedback loops
ReactTypeScriptNode.jsMongoDBGolang
MTN PulseMyMTN App
Full-time

Software Engineer

Jadaad Technologies

Jun 2024 — Nov 2024Kumasi, Ghana

Contributed to the development of Hygeieiora and Jadaad web applications, improving performance, responsiveness, and cross-device usability.

Built and maintained reusable frontend components using React, TypeScript, Material-UI, and Tailwind
Implemented user-facing features including blog functionality and real-time call alerts
Integrated backend APIs using Node.js and MongoDB
Collaborated closely with designers to deliver user-centric interfaces aligned with product requirements
Managed tasks and delivery using ClickUp, ensuring timely execution of features and updates
ReactTypeScriptTailwind CSSMaterial-UINode.jsMongoDB
HealthcareWeb Applications
Full-time

Agile Developer

Xcelsz

Jun 2023 — Aug 2023Ghana

Collaborated with a cross-functional team to improve mobile responsiveness across web products, delivering a seamless user experience across devices.

Collaborated with cross-functional team to achieve project objectives and meet sprint goals
Implemented solutions for enhancing mobile responsiveness — responsive navigation, adaptive header and hero section, optimised content layout, and responsive media
Analysed the current home page for mobile responsiveness and identified areas for improvement
Utilised CSS media queries and responsive design techniques to create a seamless experience across mobile devices
Tested and refined mobile responsiveness, incorporating user feedback and ensuring alignment with brand guidelines
ReactCSSGit
WebMobile Responsiveness
Full-time

Software Developer

DMI

Sep 2020 — Nov 2021Ghana

Led the development of Dkeys Music Institute's official website, focusing on modern UI/UX, responsive design, and SEO optimisation.

Led the development and design of the official website, focusing on modern UI/UX principles
Implemented responsive design for optimal performance across various devices
Enhanced website visibility and search engine rankings through effective SEO optimisation strategies
Collaborated with stakeholders to align project solutions with business goals
Leveraged ReactJS, HTML5, and CSS3, integrating third-party libraries for advanced functionality
Integrated social media and Open Graph Meta Tags to strengthen online brand presence
ReactHTML5CSS3
WebSEO
Full experience & certifications

Fintech Systems

Payment Infrastructure Expertise

Deep experience building the critical systems that move money — securely, reliably, and at scale in telecom and digital commerce environments.

Transaction Flow

Client App
API Gateway
Payment Engine
MoMo / Card

Mobile Money Infrastructure

End-to-end Mobile Money transaction flows including disbursements, collections, and wallet reconciliation.

MoMo APIUSSDDisbursements

Card Payment Systems

PCI DSS–compliant Mastercard hosted checkout integrations with tokenization and secure data handling.

PCI DSSMastercardTokenization

Airtime & Digital Goods

Airtime recharge pipelines with retry logic, idempotency keys, and carrier gateway integrations.

Airtime APIIdempotencyRetry Logic

OTP & Fraud Prevention

Multi-channel OTP verification and fraud prevention — SIM swap validation and Ghana Card (NIA) integration.

OTPSIM SwapNIA Integration

Transaction Observability

Real-time monitoring and alerting for payment infrastructure health using OpenTelemetry and Panorama.

OpenTelemetryPanoramaMonitoring

Resilient Architecture

Transaction flows built for graceful degradation — retries, duplicate submission handling, and async status updates.

Retry LogicIdempotencyAsync Polling

Featured Projects

Systems I've Engineered

Production systems, active development, and next-generation tools — across fintech infrastructure and music technology.

FintechProduction

MTN Pay

Central Payment Gateway

MTN Pay is the central payment gateway for MTN, integrated by multiple services including the Self Service Portal. It handles Mobile Money transactions, PCI DSS–compliant Mastercard hosted checkout, and airtime top-up.

PCI DSS–compliant Mastercard hosted checkout
Mobile Money disbursements and collections
Airtime top-up integration
OTP verification and fraud prevention
Resilient flows with retry logic and status polling
ReactTypeScriptNode.jsGolang
TelecomProduction

MTN Self Service Portal

Customer Self-Service Platform

The MTN Self Service Portal (SSP) allows customers to manage and service their MTN accounts independently. It supports broadband, data bundles, SIM management, eSIM provisioning, and more, integrated with MTN Pay for in-portal payments.

Broadband and data bundle management
SIM and eSIM provisioning
Self-service account management
Integrated with MTN Pay for payments
ReactTypeScriptNode.js
TelecomProduction

MTN Pulse

Youth Platform · MyMTN App

MTN Pulse is MTN's youth platform, delivered within the MyMTN app. The platform provides targeted offers, data bundles, and digital experiences for MTN's young subscriber base.

Youth-focused features within the MyMTN app
Targeted offers and data bundle flows
Frontend contribution 2023–2025
ReactTypeScriptNode.js
Identity & SecurityProduction

MTN Auth Services

Centralized Identity & Access

MTN Auth Services provides centralized identity and access control using Auth0, consumed by multiple MTN applications across Ghana and South Africa MTN Group, supporting secure and consistent authentication at scale.

Auth0-based centralized authentication
Consumed by multiple MTN services in Ghana and South Africa
Biometric verification integration with Metrics Africa
Supports centralized access control at scale
Auth0Node.jsTypeScript
SystemsProduction

Autosurveil GPS

Fleet Intelligence Platform

A full-stack fleet intelligence platform providing live GPS tracking, route analytics, and vehicle management. Led the full redevelopment of the platform across frontend and backend.

Led full-stack redevelopment of the platform
OTP-based authentication and onboarding flows
Route history and analytics dashboard
Multi-fleet management interface
Next.jsTypeScriptNode.jsMongoDB
Music TechnologyAvailable

PulseMIDI

MIDI Diagnostics & Monitoring

PulseMIDI is a native macOS application for MIDI signal monitoring, device management, and port routing. Built with Swift and SwiftUI, using CoreMIDI for system-level MIDI access and the CLAP SDK for plugin distribution. Ships as a universal binary targeting Apple Silicon and Intel Macs on macOS 12+.

Native Swift + SwiftUI with direct CoreMIDI framework access
Realtime MIDI signal visualisation and device enumeration
Virtual MIDI port creation and routing
Universal binary — Apple Silicon + Intel, macOS 12+
Standalone, AudioUnit v3, and CLAP plugin distributions
SwiftSwiftUICoreMIDIAudioUnit v3CLAP SDK
Music TechnologyAvailable

PulseControl Bridge

Native macOS DAW Bridge

PulseControl Bridge is a native macOS application that bridges the PulseControl Mobile app to your DAW over a local WebSocket connection. Devices discover each other via Bonjour/mDNS — no configuration required. Creates virtual MIDI output ports via CoreMIDI for seamless DAW integration.

Creates virtual MIDI output ports via CoreMIDI — appears as a real MIDI device in any DAW
WebSocket server receiving MIDI control data from mobile
Bonjour/mDNS network advertisement for zero-config device discovery
Universal binary — Apple Silicon + Intel native
macOS 11+ standalone application
SwiftNetwork.frameworkBonjour/mDNSCoreMIDI
Music TechnologyAndroid Available

PulseControl Mobile

Wireless MIDI Control Surface

PulseControl Mobile turns your phone into a wireless MIDI controller. Android is available now, with iOS coming soon. Touch faders and rotary knobs send MIDI CC data to PulseControl Bridge over a WebSocket connection. Pairing is handled via QR code — no manual network configuration.

Touch faders and rotary knobs transmitting MIDI CC data
WebSocket transport pairing with PulseControl Bridge
QR code pairing — zero manual network configuration
Android available now; iOS release in progress
React NativeWebSocketiOSAndroid
View all projects

Writing & Insights

Engineering Notebook

Thinking in public about payment systems, reliability engineering, music technology, and the craft of building software.

Fintech Engineering8 min read

Transaction Orchestration in High-Volume Payment Systems

How to design resilient transaction pipelines that handle failure gracefully — from idempotency keys to dead letter queues.

PaymentsArchitectureReliability
Coming Soon
Security6 min read

PCI DSS Compliance for Frontend Engineers

What frontend engineers building card payment flows actually need to know about PCI DSS, tokenization, and hosted checkout.

PCI DSSSecurityReact
Coming Soon
Music Technology10 min read

Building Native macOS MIDI Tools with Swift and CoreMIDI

A practical guide to accessing macOS CoreMIDI from Swift — device enumeration, virtual port creation, and real-time message handling.

SwiftMIDImacOS
Coming Soon
Reliability Engineering7 min read

Observability for Payment Systems

Building dashboards, alerts, and distributed tracing for payment infrastructure — what to measure and why it matters.

ObservabilityPaymentsSRE
Coming Soon

Articles coming soon — building in public

Read all articles

Contact

Let's build something remarkable

Whether you're building payment infrastructure, exploring creative technology, or want to talk systems engineering — I'm open to interesting conversations.

Based in Accra, Ghana

GitHub

@ernestyoyowah

LinkedIn

Ernest Yoyowah

Email

ernestniiyoyowah@gmail.com

Send a message