Сергій

Python Backend Developer
Technical Skills:
Languages: Python (Advanced), C# (Basics).
Frameworks & Libraries: FastAPI, Pydantic, aiogram, Telegram Bot API, pytest.
Cloud (AWS): Lambda, API Gateway, S3, DynamoDB, boto3, EC2, IAM, CloudWatch.
Databases: PostgreSQL, MySQL, SQLite, MongoDB (Design, Migrations, Query Optimization).
Data & Automation: ETL Processes, Data Cleaning, Selenium, Beautiful Soup, Web Scraping.
Tools & Workflow: Git (Git Flow), Code Reviews, Unit Testing.
Familiar with: Docker, Kubernetes, GitLab CI/CD, RabbitMQ.

Language Skills:
Languages: English (B1, intermediate), Ukrainian (native), Russian (native)

Professional Experience / Key Responsibilities:
• Backend & API Development: Designed and implemented high-performance RESTful
APIs using FastAPI and Pydantic for strict data validation, ensuring seamless
communication between services and frontend applications.
• Cloud Infrastructure: Built and deployed serverless solutions using AWS Lambda and API
Gateway, leveraging S3 for storage and DynamoDB for scalable NoSQL data
management.
• Data Engineering & Automation: Developed robust ETL pipelines to extract data via
Beautiful Soup and Selenium, followed by automated data cleaning and normalization to
ensure high-quality datasets.
• Database Management: Managed data integrity and performance across SQL
(PostgreSQL, MySQL) and NoSQL (MongoDB) databases; handled schema design,
complex query optimization, and automated migrations.
• Authentication: Designed and implemented secure user authentication using JWT (JSON
Web Tokens) for token-based sessions, refresh tokens, and protected routes in FastAPI
applications.
• Authorization & Access Control: Configured fine-grained access control using AWS IAM
policies for serverless resources (Lambda, API Gateway, S3, DynamoDB), ensuring
leastprivilege access and secure cross-service permissions.
• Bot Development: Engineered interactive Telegram bots using aiogram, integrating them
with backend services, ETL scripts, and external APIs.
• Quality Assurance: Maintained high code quality and system reliability through Git Flow,
rigorous code reviews, and comprehensive unit testing (pytest).

Project Experience
Project: Car Rent Application project App for automating and enhancing
operations across the "Car Rent" agencies network
Responsibilities:
• Designed and implemented APIs(FastAPI) to ensure seamless integration with front-end
components. • Optimized application performance by identifying bottlenecks and improving
code efficiency. • Collaborated with cross-functional teams to gather requirements and deliver
solutions aligned with business objectives. • Conducted code reviews and implemented best
practices to ensure high-quality and maintainable code. • Ensured application security by
implementing authentication, authorization, and data protection measures. • Troubleshot and
resolved backend issues to maintain system reliability and uptime.

Additional info:
Tools and Technologies: Python, REST API, Dependecy Injection, AWS Lambda, AWS DynamoDB,
AWS S3, AWS Cognito, AWS Simple Email Service, AWS Simple Queue Service, AWS Simple
Notification Service, AWS API Gateway, AWS IAM, Amazon EventBridge, StepFunction, AWS
CloudWatch, AWS EC2, FastAPI, MongoDb, OpenAPI Specification, Kubernetes, Postman,
RabbitMQ, Swagger. Team: 4 backend devs, 1 frontend dev, 1 BA, PM

Client: ranobe-life.com.ua
Project: Web-based service with: 1. translations 2. covers 3. descriptions 4. comments 5.
reviews 6. chat 7. personal profile 8. admin and moderator dashboards 9. roles and permissions
Tech stack: C#, AspNet, EntityFramework, PostgreSQL, REST API Team: 3 (FS, BE, FE)
Responsibilities:

• Designed and implemented REST API endpoints using C#, ASP.NET, and Entity
Framework.
• Integrated role-based validation for API endpoints to ensure proper access control.
• Developed and managed user roles and permissions, aligning with project requirements.
• Implemented robust authentication and authorization mechanisms for secure
application access.
• Designed and maintained database models, including schema migrations, in PostgreSQL.
• Built end-to-end encryption for secure chat message communication within the
application.
• Created and executed unit and integration tests to ensure code reliability and
functionality.
• Collaborated using Git flow, participated in code reviews, and contributed to sprint
planning processes.

Client: Retail and E-commerce domain, with a focus on logistics and supply chain
optimization. The client operates as a Private Entrepreneur (Sole Proprietor)
managing a small online distribution network
Project: Telegram bot for managing customer orders. Tech stack: Python + aiogram +
SQLAlchemy + OracleVM. Solo development.
Responsibilities:
Solely developed and deployed a Telegram bot service, designing the Python backend and
utilizing SQLAlchemy for efficient data persistence. The project involved implementing custom
user workflows and configuring the necessary hosting environment for continuous operation.

Implemented:

1. Order creation flow.
2. Multi language support.
3. Announcement message system.
4. Admin, moderator and user roles.
5. Admin and moderator permissions(e.g. CRUD operation for orders, order status or
announcement).
6. Sorted orders lists for admin and moderator roles, downloadable in xml and csv formats.
7. Help tickets system. 8. Order status change notification system for any role.