I'm Rostyslav Popadyn, a Senior Full-Stack Software Engineer with 10+ years of experience delivering scalable, high-performance web applications and distributed systems. I specialize in Ruby on Rails, Python (Django, Flask, FastAPI), and modern JavaScript frameworks (React, Next.js), with a strong focus on end-to-end SaaS solutions. I design RESTful and GraphQL APIs, integrate third-party services, and develop responsive front-end interfaces. I work with relational and NoSQL databases and deploy cloud-native apps across AWS, Azure, and GCP using Docker, Kubernetes, and Terraform. I build clean, maintainable architectures, implement CI/CD pipelines, and optimize production performance. I'm experienced across fintech, healthtech, satellite data, blockchain, and AI projects, collaborating with cross-functional teams to deliver scalable, reliable software. I enjoy turning complex requirements into robust systems and staying current with evolving tech trends.…

Rostyslav Popadyn

I'm Rostyslav Popadyn, a Senior Full-Stack Software Engineer with 10+ years of experience delivering scalable, high-performance web applications and distributed systems. I specialize in Ruby on Rails, Python (Django, Flask, FastAPI), and modern JavaScript frameworks (React, Next.js), with a strong focus on end-to-end SaaS solutions. I design RESTful and GraphQL APIs, integrate third-party services, and develop responsive front-end interfaces. I work with relational and NoSQL databases and deploy cloud-native apps across AWS, Azure, and GCP using Docker, Kubernetes, and Terraform. I build clean, maintainable architectures, implement CI/CD pipelines, and optimize production performance. I'm experienced across fintech, healthtech, satellite data, blockchain, and AI projects, collaborating with cross-functional teams to deliver scalable, reliable software. I enjoy turning complex requirements into robust systems and staying current with evolving tech trends.…

Available to hire

I’m Rostyslav Popadyn, a Senior Full-Stack Software Engineer with 10+ years of experience delivering scalable, high-performance web applications and distributed systems. I specialize in Ruby on Rails, Python (Django, Flask, FastAPI), and modern JavaScript frameworks (React, Next.js), with a strong focus on end-to-end SaaS solutions. I design RESTful and GraphQL APIs, integrate third-party services, and develop responsive front-end interfaces. I work with relational and NoSQL databases and deploy cloud-native apps across AWS, Azure, and GCP using Docker, Kubernetes, and Terraform. I build clean, maintainable architectures, implement CI/CD pipelines, and optimize production performance.

I’m experienced across fintech, healthtech, satellite data, blockchain, and AI projects, collaborating with cross-functional teams to deliver scalable, reliable software. I enjoy turning complex requirements into robust systems and staying current with evolving tech trends.

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Skills

Experience Level

Ruby on Rails
Expert
Python
Expert
Golang
Expert
Kubernetes
Expert
Django
Expert
PostgreSQL
Expert
Node.js
Expert
JavaScript
Expert
AWS
Expert
MongoDB
Expert
TypeScript
Expert
SQL
Expert
React JS
Expert
Google Cloud
Expert
MySQL
Intermediate
Redis
Intermediate
Azure
Intermediate
Selenium
Beginner
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Language

English
Fluent
Russian
Fluent
Ukrainian
Fluent

Work Experience

Senior Full-Stack Developer at Upwork.com
August 1, 2019 - Present
Designed and deployed multiple Python/Django REST APIs and event-driven microservices for fintech and healthtech clients. Built scalable backend systems using Python, Flask, and FastAPI integrated with PostgreSQL and MongoDB. Managed Kubernetes deployments (AKS/EKS) with zero downtime, implementing Helm charts and CI/CD pipelines via Azure DevOps & GitHub Actions. Automated infrastructure provisioning using Terraform for multi-cloud environments (AWS, Azure). Integrated monitoring with Prometheus/Grafana, implemented logging best practices, and optimized API performance by 40%.
Senior Ruby on Rails Developer at Web DevStar -LLC
October 1, 2024 - Present
Designed and developed scalable Ruby on Rails applications, including RESTful APIs and SaaS platforms. Built backend systems using Rails, PostgreSQL, and Redis, ensuring performance and reliability. Implemented background job processing with Sidekiq for asynchronous workflows. Structured applications using MVC architecture, ActiveRecord, and service-oriented design. Integrated third-party services (Stripe, analytics, external APIs) and implemented secure authentication (JWT, OAuth2). Deployed and scaled applications using Docker, Kubernetes, AWS, and Azure. Optimized database queries and application performance, improving response times and system efficiency. Collaborated with frontend teams (React/Next.js) to deliver full-stack solutions.
Senior Backend Developer at Open-Cosmos
June 1, 2024 - September 30, 2024
Led the modernization of a satellite data platform by architecting and implementing a distributed microservices system using .NET 7 and Golang, enabling high-availability telemetry data processing across multiple regions. Designed and developed event-driven services using Azure Functions (Durable & Timer Triggers) to handle large volumes of space-borne sensor data with precision timing and fault tolerance. Collaborated closely with DevOps to implement infrastructure-as-code (IaC) using Terraform, optimizing CI/CD pipelines in Azure DevOps for weekly, zero-downtime deployments. Integrated Azure Key Vault, Managed Identities, and secure API gateway patterns to enforce compliance with aerospace-grade security standards. Mentored a distributed backend team on clean architecture principles, logging/monitoring strategies, and test automation. Introduced data validation and normalization routines in Golang for satellite payloads, reducing ingest processing time by 30%.
Senior Backend Developer at Ciklum
March 1, 2024 - June 30, 2024
Developed Python-based ingestion pipelines for aggregating and normalizing data from external APIs into Snowflake. Deployed and managed Kubernetes workloads with horizontal scaling for high-volume data processing. Built REST APIs in Python and Golang, ensuring secure authentication and data validation. Automated deployments using Terraform and Azure DevOps.

Education

Bachelor’s Degree at State University Lviv Polytechnic
January 11, 2030 - April 1, 2012
Diploma at Lviv Academy of Commerce
January 11, 2030 - April 1, 2017

Qualifications

Web Development w/ Google’s Go (Golang) Programming Language
January 11, 2030 - April 18, 2026
AWS Certified Solutions Architect – Associate
January 11, 2030 - April 18, 2026
Blockchain Security Professional
January 11, 2030 - April 18, 2026
Certified Associate JavaScript Programmer Certification
January 11, 2030 - April 18, 2026
Certified Associate in Python Programming
January 11, 2030 - April 18, 2026

Industry Experience

Software & Internet, Computers & Electronics, Professional Services, Media & Entertainment, Financial Services, Healthcare, Other
    paper Senior Full-Stack Engineer (Backend & Cloud Systems)

    Led the design and development of scalable web applications and distributed systems for fintech, blockchain, and data-driven platforms. Built high-performance backend services, APIs, and microservices while ensuring reliability, security, and scalability across cloud environments.