Performed manual testing of Windows desktop applications and Windows Services, including functional, system, smoke, regression, integration, and E2E testing. Performed end-to-end testing across POS applications, Windows Services, databases, and external systems, validating complete data flows and business scenarios. Tested integrations between POS software and third-party or internal systems, validating data exchange, synchronization, and integration workflows. Tested Windows Services responsible for bidirectional synchronization between local and central databases, verifying synchronization results and data consistency. Performed REST API testing using Postman and Swagger/OpenAPI (GET, POST, PUT, PATCH, DELETE), validating status codes, headers, request/response bodies, and JSON/XML payloads. Worked with Microsoft SQL Server, including SELECT and JOIN queries, INSERT/UPDATE/DELETE operations, SQL scripts, stored procedures, database structure, table relationships, and data verification during application and integration testing. Analyzed application and Windows Service logs, configuration files, Event Viewer, and network diagnostics to investigate integration, synchronization, backend, and connectivity issues. Analyzed requirements and specifications, prepared test cases and checklists in Qase, and verified actual system behavior against expected requirements. Created detailed bug reports, tracked defects and issues using GitLab, OTRS, and Trello, and collaborated with developers during investigation, retesting, and regression testing. Configured and troubleshot test environments involving Windows Services, application configuration files, database connections, IIS components, and network connectivity. Performed defect verification and retesting after fixes, followed by regression testing to ensure existing functionality remained stable.

Provided L1–L3 technical support for hotel and restaurant management software, progressing from basic incidents to complex technical issues. Installed, configured, updated, and maintained client software and related components in Windows environments. Worked with Microsoft SQL Server using SSMS and SQL Profiler, including database deployment, SQL queries and scripts, data analysis, troubleshooting, and basic backup/restore operations. Diagnosed and resolved Windows 7/10/11, application, Windows Service, network, and connectivity issues on client machines. Installed, configured, restarted, and troubleshot Windows Services and analyzed application, service, and system logs to identify root causes of incidents. Deployed and maintained IIS websites and related server components in Windows environments. Performed network and connectivity troubleshooting using TCP/IP, DNS, ports, VPN, RDP, ping, telnet, and nslookup. Worked with remote access and virtualization tools, including RDP, AnyDesk, TeamViewer, VMware, and VirtualBox. Managed support tickets using OTRS and worked with SIP telephony systems. Communicated directly with clients, developers, and internal teams to investigate issues and ensure timely and effective problem resolution.