Sergii Kucherenko
.NET Backend Developer
summary
Backend developer building APIs and working with infrastructure on AWS - from PayPal and DAFpay integrations to legacy refactoring into modern services on ECS Fargate and EC2. Looking for backend and devops work, a modern stack and AI-assisted workflows.
Experience
RemSoft.Dev - Middle ASP.NET + SQL Developer
Fundraising platform for 5,000+ nonprofits and 4M donors.
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Replaced manual releases with two-stage CI/CD and tracked SQL migrations, split between CodeDeploy to EC2 and ECR to ECS Fargate with OpenTelemetry
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Owned DAFpay integration from estimate to production, with HMAC verification and idempotent webhooks
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Developed fee reconciliation over PayPal Classic API (NVP and SOAP) on EF6, recovering 60-100 donations that had taken 3-4 hours to backfill by hand monthly, plus an admin API that cleared 8 years of backlog
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Extracted email and file handling into standalone minimal Web API services, orchestrated locally with Aspire, adding provider-agnostic fallbacks and moving storage to S3 with CDN and access-checked streaming
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Drove legacy minimization and hardening - .NET 4.5 to 4.8, 25 projects down to 7, builds 3x faster - unifying unit testing, rebuilding CSRF protection and input sanitization, and moving secrets to AWS Secrets Manager
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Initiated team-wide Claude Code adoption, with conventions and MCP servers for Jira, SQL Server and Git
MeetPoint - Full-stack Developer
Non-commercial team project - meetup planner.
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Built the backend as an ASP.NET Core Web API on clean architecture, with PostgreSQL and EF Core, JWT auth over ASP.NET Identity, a SignalR Redis backplane and Docker Compose for local runs
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Integrated Google Maps APIs into the Angular frontend, computing distances locally to avoid repeat calls
Projects
Claude Code multi-repo knowledge system - GitHub
Agentic development workspace for a legacy multi-repo .NET codebase.
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Authored, benchmarked and iterated 11 skills for explore, review and QA workflows
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Cached codebase facts and pitfalls in staleness-checked maps, with a Python grader, linters and deny rules
ETL CLI tool - GitHub
Console tool for preprocessing and bulk-importing large datasets into SQL Server.
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Implemented streamed CSV import with CsvHelper and FastMember, without loading files into memory
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Designed preprocessing and SqlBulkCopy load into a SQL Server schema with computed columns and indexes
Skills
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Backend: C#, .NET 10, ASP.NET Core (Web API, MVC, Razor), Aspire, .NET Framework 4.x (Web Forms)
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Databases: SQL Server (T-SQL), EF Core, PostgreSQL, Redis
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Integrations: payments (PayPal, DAFpay, Stripe), email (Mailgun, SMTP), REST, SOAP, NVP, webhooks
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Infrastructure: AWS (ECR, ECS (Fargate), EC2, S3, Secrets Manager, CloudWatch), OpenTelemetry
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CI/CD and testing: Bitbucket Pipelines, AWS CodeDeploy, Docker, xUnit, NUnit, Moq, Postman
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AI tooling: Claude Code, MCP servers, agent workflow automation (hooks, custom skills, codebase maps)
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Frontend: TypeScript, Angular (RxJS), JavaScript, AngularJS, jQuery
Education
Bachelor of Software Engineering, Faculty of Applied Mathematics
National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute"