10/11/2026 updated
OS
100 % available
Senior Backend Engineer (.NET / C#)
Valencia, Spain
Only remote
Specialist Diploma (5-year degree) - Saint Petersburg State University of Aerospace InstrumentationAbout me
Senior C#/.NET backend engineer and hands-on Tech Lead (6 years) based in Valencia, Spain. ASP.NET Core, SQL Server/PostgreSQL, AWS, event-driven microservices, React/TypeScript. Fully remote for EU clients, English C1, AI-assisted development (Claude Code/Codex).
.NET / C# Backend Development
Expertise in building and running production backend systems using C#, .NET 10/8/6, .NET Core 3.1, .NET Framework 4.8, ASP.NET Core Web API and MVC, REST, gRPC, microservices, async programming, LINQ, Dapper, Entity Framework Core, Autofac, and AutoMapper.
Cloud & DevOps
Hands-on experience with AWS (EC2, S3, Lambda, IAM, CloudWatch), Docker, Terraform, Azure DevOps Pipelines, and GitHub Actions for cloud infrastructure, delivery, and deployment automation.
Data & Search
Proficiency with SQL Server/T-SQL, PostgreSQL, MySQL, DynamoDB, Snowflake, Redis, Elasticsearch/OpenSearch, query optimization, and caching strategies.
Messaging & Event-Driven Architecture
Experience with RabbitMQ, AWS SQS/SNS/EventBridge, event-driven architecture, idempotency, retries, Polly, and rate limiting for reliable distributed systems.
Security & Integrations
Knowledge of OAuth2, OpenID Connect, SSO, JWT, OpenAPI/Swagger, and third-party API integrations, including designing reusable SSO/OpenID Connect frameworks.
Quality & Observability
Application of xUnit, NUnit, Moq, FluentAssertions, TDD, integration testing, Serilog, Kibana, and Logz.io for quality assurance and production observability.
AI-Assisted Development
Practical use of AI-DLC, Claude Code, Codex, GitHub Copilot, Cursor, and Antigravity to support and accelerate the software development lifecycle.
Frontend Technologies
Supplementary skills in React, TypeScript, Redux, Node.js, and Express for full-stack contributions.
Expertise in building and running production backend systems using C#, .NET 10/8/6, .NET Core 3.1, .NET Framework 4.8, ASP.NET Core Web API and MVC, REST, gRPC, microservices, async programming, LINQ, Dapper, Entity Framework Core, Autofac, and AutoMapper.
Cloud & DevOps
Hands-on experience with AWS (EC2, S3, Lambda, IAM, CloudWatch), Docker, Terraform, Azure DevOps Pipelines, and GitHub Actions for cloud infrastructure, delivery, and deployment automation.
Data & Search
Proficiency with SQL Server/T-SQL, PostgreSQL, MySQL, DynamoDB, Snowflake, Redis, Elasticsearch/OpenSearch, query optimization, and caching strategies.
Messaging & Event-Driven Architecture
Experience with RabbitMQ, AWS SQS/SNS/EventBridge, event-driven architecture, idempotency, retries, Polly, and rate limiting for reliable distributed systems.
Security & Integrations
Knowledge of OAuth2, OpenID Connect, SSO, JWT, OpenAPI/Swagger, and third-party API integrations, including designing reusable SSO/OpenID Connect frameworks.
Quality & Observability
Application of xUnit, NUnit, Moq, FluentAssertions, TDD, integration testing, Serilog, Kibana, and Logz.io for quality assurance and production observability.
AI-Assisted Development
Practical use of AI-DLC, Claude Code, Codex, GitHub Copilot, Cursor, and Antigravity to support and accelerate the software development lifecycle.
Frontend Technologies
Supplementary skills in React, TypeScript, Redux, Node.js, and Express for full-stack contributions.
Experience
Professional experience5 - 10 years
Freelancer since2026
Languages
EnglishFluentRussianNative speakerSpanishBasic knowledgeHebrewBasic knowledge
Project history
As Tech Lead from January 2024, owned architecture, technical decisions, design and code reviews, and production quality for backend-heavy features in C#/.NET on an AI-driven recruitment advertising platform. Architected and shipped the LinkedIn Pay-for-Performance integration end to end, built cookie-less tracking via browser fingerprinting, developed event-driven integrations with RabbitMQ and AWS SQS/SNS/EventBridge, built the main client dashboard, designed a reusable SSO/OpenID Connect framework, deployed a high-availability Redis setup, migrated services to AWS with Terraform, and helped establish the company's AI-driven development lifecycle (AI-DLC).
Built backend services and REST APIs for CRM and client-account products using .NET Core 3.1 / .NET 6 and SQL. Integrated 20+ third-party payment providers, handled production issues with fast incident response, contributed to a PCI DSS certification project as a mandatory reviewer for quality- and security-sensitive changes, and applied TDD with xUnit and NUnit to reduce regressions.