Senior Backend Developer
Back-end Engineer
Available for hire
Years of
experience
8+ years
Experience
level
Senior
Available from
26 Jun 2026
I'm Cosmos Appiah, a Senior Software Engineer with 8+ years of experience building scalable backend systems and mobile applications. My work spans fintech platforms, AI-powered voice agents, microservices architectures, and React Native mobile apps shipped to both the Play Store and App Store.
Skills
JavaScript
TypeScript
Laravel
React.js
Next.js
NestJS
Vue.js
TensorFlow
Node.js
Express.js
Tailwind CSS
SQL
Web sockets
GraphQL
Playwright
Docker
AWS
Azure
Vercel
Blockchain
WebGL
GCP
Zod
NoSQL
Lambda
Kubernetes
Terraform
Web3
jQuery
Three.js
JWT
Ethers.js
ESLint
Material UI
Natural Language Processing
MERN stack
MongoDB
PostgreSQL
MySQL
Firebase
Dynamodb
Firestore
Git
Prisma
CI/CD
Machine Learning
Stripe
Webhook
Smart Contract
Crypto
Flutter
Webflow
Python
Java
PHP
Go
Kotlin
Dart
.NET
Django
FastAPI
Ruby on Rails
Qt
Hugging Face
Gradle
Languages
Employment History
Senior Backend Engineer at
TechHalo
2025
-
2026
- Built and maintained agentic voice agents with Elevenlabs.
- Designed and deployed a microservices architecture (10+ services) using Node.js
and cloud infrastructure.
- Built backend systems powering AI voice agents using LLM integrations.
- Improved system scalability and reliability for real-time processing.
- Took a lead role in the company building their own proprietary ai voice agent.
Senior Backend Engineer at
CreativeOS
2024
-
2025
- Took lead on the platform payment migration from Stripe to Chargebee.
- Developed RESTful and GraphQL APIs to support frontend applications.
- Took lead on the User management migration from Memberstack to Workos.
- Built and deployed AI services using LLMs.
Lead Mobile Engineer at
Akwaaba App
2023
-
2023
Led the development of the mobile application for Play Store and App store.
Cofounder at
SeevCash
Current
2022
-
Now
- Leading the technical side of things contributing greatly to development and improvement of Mobile App and Backend Server.
- Created a price discovery search engine with Meilisearch for users to search for
goods and services around them.
- Integrating Stellar blockchain to support peer to peer international transfers.
Tech Lead at
Hodlpay
2022
-
2024
- Head the tech team and was mainly in charge of the Backend System and Mobile App.
- Built a crypto swap aggregator that integrates multiple exchanges for users to have more option when swapping crypto.
- Automated the buy and sell crypto feature improving performance leading to the platform making 160,000 USD in sales quarterly.
Senior Mobile and Backend Engineer at
BB Universe
2022
-
2023
- Led a team of two built the Candor Mobile app in react native for Play store and App Store.
- Led a team of 2 to build the hallway mobile app for Play store and App store.
Backend Engineer at
Bezomoney
2021
-
2022
- Built a multi-vendor payment gateway that allows transactions to be fulfilled using any integrated vendor the processed over 5000 transactions monthly.
- Contributed to building the USSD application which serves over 1000 users a month.
Full Stack Developer at
Speednance
2020
-
2020
Built and deployed the speednance.com web app and backend from scratch.
Frontend Developer at
IGNIS Technologies
2019
-
2020
- Built and deployed the company's landing page.
- Built and deployed the IGNIS CONSTRUCTION website.
Education
Bachelor of Science in Computer Science (Second Class Upper Division) at
University of Ghana
2019
-
2023