Aduax Customs Agency, a leading company in customs innovation and technology, is seeking: * **Senior .NET & Cloud Integrations Developer (Freelance)** **About the Role:** We are looking for an expert to maintain and modernize critical integration workflows at **Aduax**. Your mission will be to connect systems, optimize Windows services, and migrate business logic to serverless architectures on AWS. **Key Responsibilities:** * **Backend Development:** Maintenance of C# applications (.NET Core/6+ and Legacy Framework) and optimization of Windows Services. * **Data Integration:** Automation of file ingestion and processing (XML, CSV, EDI) via SFTP/FTPS. * **Database:** SQL Server tuning, complex Stored Procedures, and production performance diagnostics. * **Cloud (AWS):** Migration of business logic to AWS Lambda and integration with S3, SQS, and EventBridge. * **QA & Support:** Design of unit tests (xUnit/NUnit) and autonomous incident diagnosis through log analysis. **Requirements (Must-Have):** * **Senior Experience:** Expert-level proficiency in C# and advanced SQL. * **Technical Stack:** .NET Framework 4.8+, .NET Core 6/8, and ASP.NET Web API. * **Cloud:** AWS Lambda, S3, and API Gateway. * **Testing:** Solid experience in Unit Testing and mocking libraries. * **Protocols:** In-depth knowledge of FTP/SFTP. **What We Offer:** * 100% remote work (Central Time Zone / Mexico preferred). * Freelance engagement based on objectives. * Technical challenge: Transition of mission-critical on-premises systems to serverless. Job Type: Full-time Salary: $30,000.00 - $40,000.00 per month Work Location: Remote