Michel Vianey BAYOI, Developer in Douala, Cameroon
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Michel Vianey BAYOI

Verified Expert  in Engineering

Software Developer

Douala, Cameroon
Toptal Member Since
July 21, 2022

Michel is passionate about the JavaScript world, including Node.js, React, Vue, and TypeScript. As a full-stack developer, he loves coding complex back-end features and building splendid user interfaces. Michel believes that the most significant achievements are the result of teamwork. His first concern is being well integrated into a team and communicating proactively. He is a hard worker and a fast learner.


Amazon Web Services (AWS), GraphQL, React, Node.js, TypeScript, Docker...
Algorithms, Amazon Web Services (AWS), Amazon API Gateway, Amazon S3 (AWS S3)...
Node.js, React, Amazon Web Services (AWS), Firebase...




Preferred Environment

Amazon Web Services (AWS), Firebase, Node.js, GraphQL, React, TypeScript, PostgreSQL, REST, Microservices, Prisma

The most amazing...

...thing I've developed was a package to authenticate and communicate with some of the major EHRs and EMRs such as Cerner, Athena, and Epic.

Work Experience

JavaScript Software Engineer

2021 - PRESENT
  • Involved in the dining service creation. I implemented a part of the GraphQL server and the UI components that allows the user to search, create, and edit menu items and display them in a menu panel inside the dining module.
  • Implemented a module that scraps the publications made on the website and creates regular publications displayed on the mobile application. This feature increased the engagement of the residents.
  • Developed a web view for the mobile app that allows users to check their account balance and expense details. This web view was a Next.js application hosted inside an AWS Lambda function.
Technologies: Amazon Web Services (AWS), GraphQL, React, Node.js, TypeScript, Docker, React Apollo, Apollo Server, REST, PostgreSQL, Database Design, Algorithms, Kubernetes, Next.js, AWS Lambda, Amazon API Gateway, Amazon DynamoDB, Amazon S3 (AWS S3), Redis, Express.js, Amazon EKS, JavaScript, HTML, CSS, Redux, SQL, Full-stack Development, Serverless, APIs, Full-stack

Senior Software Engineer

2020 - 2020
  • Developed an internal data population tool. This Node.js application written in TypeScript exposed a REST API that allows automating the creation of demo environments for potential customers. This led to a 55% increase in user retention.
  • Developed the front-end side of an ERP's expenses module. This module allows users to create and track their expenses and provides a useful overview of the evolution of expenses over time through intuitive charts.
  • Made the migration of the entire React application from JavaScript to TypeScript. In addition to improving code robustness and maintainability, this has led to a 70% decrease in bugs.
Technologies: Algorithms, Amazon Web Services (AWS), Amazon API Gateway, Amazon S3 (AWS S3), AWS Lambda, Node.js, Docker, React, Redux, TypeScript, PostgreSQL, Prisma, Express.js, Redis, REST, Microservices, Amazon EKS, OpenAPI, Postman, Database Design, JavaScript, HTML, CSS, React Redux, Jest, SQL, Full-stack Development, APIs, Full-stack

Senior Software Engineer

2019 - 2020
  • Designed the general architecture of a patient management application choosing databases, cloud providers, services, front-end technologies, and a way to connect them efficiently.
  • Implemented the most sensitive back-end features like data modeling, API contract design with Open API specification, patient data processing, and authentication.
  • Set up the CI/CD workflow to automate tests and deployments using mainly GitHub Actions.
  • Developed complex React components according to the UI designer's specifications, namely a form builder.
Technologies: Node.js, React, Amazon Web Services (AWS), Firebase, Fast Healthcare Interoperability Resources (FHIR), Google Cloud Platform (GCP), TypeScript, Postman, Docker, Kubernetes, MongoDB, Algorithms, Cloud Firestore, Google Cloud Functions, Google Cloud Storage, Healthcare, Google Cloud API, Redux, OpenAPI, JSON Web Tokens (JWT), OAuth 2, Express.js, JavaScript, HTML, CSS, Full-stack Development, Serverless, APIs, Full-stack

Full-stack Software Engineer

2017 - 2019
  • Maintained and improved a financial application built with Electron and React called "Fit for ISO 20022". I improved the algorithm that transforms the financial orders to the ISO 20022 format.
  • Created testable, reusable, and elegant React components for the application Fit for ISO 20022 settings page.
  • Built a web application with Laravel for collecting and monitoring real estate offers in the Czech Republic. The application notifies the customer when an offer fits his requirements.
Technologies: Node.js, React, Laravel 5, Vue 2, Amazon Web Services (AWS), PHP, Electron, PostgreSQL, Algorithms, JavaScript, HTML, CSS, Redux, React Redux, SQL, Full-stack Development, APIs, Full-stack

Senior Living Technology Solutions for Older Adults

K4connect is a US fast-growing mission-driven healthtech enterprise. The company provides smart homes and technology solutions for seniors and people with disabilities using the latest state-of-the-art technology.

I worked mainly on the dining module, which allows the platform administrators to manage the restaurants, the menus, and the dishes that compose it to allow users to consult the menus adapted to their diet, access the nutritional information, and even pay.

I was in charge of developing the main graphical interfaces and collaborated with the tech lead to realize the GraphQL API of this service.

Patient's Presence Management

Worked on an application for a Seattle-based company to build a product called Aquii. This is an application that allows hospitals to manage specific processes, including automatic appointment reminders and the management of patient forms.

As a senior software engineer, I had to lead the web team and coach two junior developers.

Swift Payment Messaging

A desktop and Saas application that allows small and medium-sized enterprises that cannot upgrade their business software to handle ISO 20022 transactions.

Worked as a full-stack developer to improve the algorithm that transforms the old transaction formats and ISO 20022 transactions, resulting in a 50% increase in performance and the support of all transaction formats. I also improved the user interface and built a new settings module entirely.

An ERP Designed for A Mobile Experience

Worked on Dillali ERP during its early steps. This application offers all the features of a classic ERP but focuses on an intuitive experience on mobile and was massively adopted in developing countries like Nigeria.

As a full-stack developer, I built the user interfaces for invoices and expenses, which were fully responsive and guaranteed a fluid experience on mobile. I also built an internal tool to automate the data population for the demo.
2012 - 2017

Master's Degree in Computer Science

Polytechnic School of Yaoundé - Yaoundé, Cameroun


AWS Certified Developer – Associate

Amazon Web Services

AUGUST 2022 - AUGUST 2025

AWS Certified Solutions Architect Associate



Udemy Certification in Microservices



Node.js, React, OpenAPI, React Redux, Vue 2, Google Cloud API


Postman, Prisma, React Apollo, Amazon EKS, Mongoose, AWS CLI, AWS IAM


Redux, JSON Web Tokens (JWT), OAuth 2, Express.js, Laravel 5, Electron, Next.js, Koa, Jest


REST, Database Design, Microservices, Microservices Architecture, Fast Healthcare Interoperability Resources (FHIR)


JavaScript, TypeScript, UML, PHP, HTML, CSS, SQL, GraphQL


Firebase, AWS Lambda, Docker, Google Cloud Platform (GCP), Kubernetes, Amazon Web Services (AWS)


Amazon S3 (AWS S3), Cloud Firestore, PostgreSQL, MongoDB, Amazon DynamoDB, Redis, Google Cloud Storage

Industry Expertise



Algorithms, OOP Designs, Google Cloud Functions, Numerical Methods, Apollo Server, RESTful Microservices, ISO 20022, Amazon API Gateway, API Gateways, Full-stack Development, Serverless, APIs, Full-stack, Machine Learning, Numerical Analysis, Cloud Architecture, AWS Cloud Architecture, Cloud Services, Data, Cloud Infrastructure, Cloud

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