Maryan Mandzyuk — Software Engineer (Node.js/React.js)

Expertise in Full Stack Web (5.5 yr.), Back-End Web (5.5 yr.).

Last verified on March, 2026

Core Skills

Bio Summary

Senior Full-Stack Engineer with 5+ years of experience specializing in Node.js, TypeScript, React, and cloud-native environments (AWS & GCP).
Proven expertise in designing and developing high-throughput microservices, including Kafka consumer services processing 75K messages/min with efficient backpressure handling.
Skilled in building scalable backend systems with Nest.js, Express.js, PostgreSQL, MongoDB, Redis, and implementing robust CI/CD pipelines using GitLab and GitHub Actions.
Experience in integrating complex APIs such as Facebook Marketing API and implementing caching strategies to optimize performance under high load.
Strong background in full SDLC, automated testing (Vitest, Jest, Mocha), and cloud infrastructure management (AWS Lambda, SQS, GCP PubSub, Kubernetes), delivering secure and maintainable solutions.

Technical Skills

Programming Languages	TypeScript
JavaScript Frameworks	Express, NestJS, Node.js, React
JavaScript Libraries and Tools	Mobx, Redux-Saga, SinonJS, Zustand
Databases & Management Systems / ORM	MongoDB, MySQL, PostgreSQL, Redis, Sequelize, Typeorm
UI Frameworks, Libraries, and Browsers	Material UI, Storybook, Tailwind CSS
Cloud Platforms, Services & Computing	AWS, GCP
Amazon Web Services	AWS CDK, AWS Cognito, AWS Lambda, AWS S3, AWS SNS, AWS SQS
BlockChain and Decentralized Software	Chai
QA, Test Automation, Security	Cucumber, Jest, Mocha, Postman, Unit Testing
Logging and Monitoring	Datadog
Virtualization, Containers and Orchestration	Docker, Kubernetes
SDK / API and Integrations	Facebook API, Stripe
Version Control	Git, Github Actions
Deployment, CI/CD & Administration	GitLab CI
Message/Queue/Task Brokers	Kafka
Methodologies, Paradigms and Patterns	Publish/Subscribe Architectural Pattern
Other Technical Skills	Drizzle, RDS

Work Experience

Backend developer - TemaBit (Gym management SaaS)

Duration: May 2025 - Present
Summary:

A SaaS platform for managing gym operations including pricing and integration with AWS services
The project aims to provide scalable and reliable gym management solutions leveraging cloud infrastructure

Responsibilities:

Designed and developed system-critical modules like pricing from scratch.
Set up local and CI/CD environments for integration testing with AWS services such as SQS, EventBridge, and S3 using LocalStack.

Technologies: TypeScript, Nest.js, AWS, CDK, PostgreSQL, Drizzle, Gitlab CI/CD

Backend developer - Optimove (Email marketing platform)

Duration: Jun 2023 - May 2025
Summary: An email marketing platform designed to handle large scale marketing campaigns and user engagement through integration with social media APIs and high-throughput message processing.
Responsibilities:

Developed integration with Facebook Marketing API handling campaigns for up to 20 million users daily.
Designed and developed a high-throughput Kafka consumer service using Node.js streams for efficient backpressure handling and reduced memory overhead.
Identified and fixed critical production bugs and memory leaks to improve system stability and performance under high load.
Implemented caching strategies using Redis and in-memory caching to optimize response times and reduce database load.

Technologies: JavaScript, Express, GCP, PubSub, Kafka, MongoDB, MySQL, Redis, Mocha, Chai, Sinon, Docker, Kubernetes, DataDog

Full-stack developer - SoftServe (Global user service with admin dashboard)

Duration: Nov 2021 - Jun 2023
Summary: A global user management service with an admin dashboard used by five different EdTech products to manage users, import data, send emails, and handle event notifications.
Responsibilities:

Developed backend service and frontend admin panel for user management.
Created API routes for user management, CSV import, email sending, and event notifications.
Implemented API and integration tests using Postman CLI and GitHub actions.
Developed frontend user management interface in React using a pre-built component template.

Technologies: TypeScript, SST, AWS Lambda, S3, SQS, SNS, MongoDB, React, Redux, TailwindCSS

Full-stack developer - SoftServe (Interactive whiteboard)

Duration: Nov 2021 - Jun 2023
Summary: An interactive whiteboard product prepared for security certification by adding feature flags and enhancing testing coverage with API and end-to-end tests.
Responsibilities:

Prepared product for security certification by adding feature flags.
Created new API tests and end-to-end tests to ensure product quality and security.

Technologies: TypeScript, Express.js, Cucumber, Gherkin

Backend developer - Incora (Healthcare platform for sports clubs and schools)

Duration: Nov 2020 - Nov 2021
Summary: A healthcare platform designed to manage players of sports clubs and school students, including authentication, role-based access, booking, payments, and reporting.
Responsibilities:

Designed and developed the entire backend system from scratch to production release.
Implemented authentication, role-based access control, CRUD operations, CSV user import, email sending, appointment booking, and one-time payments with Stripe.
Developed functionality to generate statistical reports in CSV and PDF formats.

Technologies: TypeScript, NestJS, AWS Elastic Beanstalk, RDS, Lambda, Cognito, S3, PostgreSQL, TypeORM, Redis, Bull, Stripe

Full-stack developer - Freelance (Online video streaming and quizzes platform)

Duration: Jun 2020 - Nov 2020
Summary: A platform for online video streaming and quizzes, enabling users to create, manage, and export quizzes with image upload and editing features.
Responsibilities:

Designed and developed quiz management system backend and frontend components.
Implemented CSV export of quiz data.
Developed image upload feature with cropping tool for quiz images.

Technologies: TypeScript, Express.js, PostgreSQL, Sequelize, React, MobX, Storybook, Material-UI

Certification

Pure code and design patterns

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