Denys

Denys
Email: [open contact info](look above in the "contact info" section)

GitHub: https://github.com/denuntren

OBJECTIVE
Junior QA Engineer (API & UI Automation) with backend development experience in C# /
ASP.NET Core. Focused on testing REST APIs, validating business logic, and ensuring
reliability of backend systems including integrations with external APIs.

TECHNICAL SKILLS
REST API testing (positive & negative scenarios)

HTTP status code validation (200, 201, 400, 401, 403, 404, 409)

Swagger / OpenAPI contract validation

Idempotency & retry behavior testing

Transaction integrity validation

Concurrency & race condition testing

Broken Access Control & IDOR detection

Playwright (TypeScript) – End-to-End UI automation

JWT authentication validation via localStorage

Postman (Collections, scripts, Collection Runner)

SQL (JOIN, GROUP BY, HAVING, SUM, COUNT)

PostgreSQL, MongoDB

Git

C# / ASP.NET Core backend architecture understanding
PROFESSIONAL DEVELOPMENT EXPERIENCE
Junior Backend C# Developer

Commercial experience developing backend services using C# and ASP.NET Core.

Designed and implemented REST APIs and backend business logic.

Worked with PostgreSQL, MongoDB and SQL databases for data storage and validation.

Integrated and worked with third-party APIs including OpenAI API, Binance API and
MediaStack API.

Performed functional and integration testing of features related to external APIs, validating
request payloads, response structures and error handling scenarios.

Participated in debugging, troubleshooting and validating API integrations.

Collaborated with a tech lead and participated in code reviews.

PROJECT EXPERIENCE
Order System (GitHub): https://github.com/denuntren/OrderSystem

Developed and tested REST APIs built with ASP.NET Core.

Validated business logic and database consistency.

Identified race conditions and idempotency issues.

Detected IDOR (Broken Access Control) vulnerabilities.

Tested features integrating OpenAI API, validating request structure and response payloads.

Implemented Playwright E2E automation for login and protected routes.

EDUCATION
Computer Science student, Igor Sikorsky Kyiv Polytechnic Institute (2023–2027)

ENGLISH
B1–B2 (Intermediate)