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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior .NET Developer - Payment Systems & Integrations - **Company:** TalentFish LLC - **Location:** Lisle, IL, United States - **Experience:** Expert - **Salary:** $135,200.0 - $156,000.0 - **Contract:** Contract - **Skills:** Clean Code Principles, ASP.NET, JavaScript (Programming Language), .NET Framework, ADO.NET, Application Programming Interfaces (APIs), Artificial Intelligence, HTML5, Unit Testing, Microsoft Azure, Bootstrap (Software), C Sharp (Programming Language), Cascading Style Sheets (CSS), Code Review, Continuous Integration, IBM DB2, Relational Databases, Software Design Patterns, DevOps, Payment Systems, Entity Framework, Github, Windows Communication Foundation, JQuery, PostgreSQL, Microsoft Visual Studio, Microsoft Software, Microsoft SQL Server, Team Foundation Server, Model View Controller (MVC), Object-Oriented Software Development, Oracle (Applications), Payment Service Provider, Performance Tuning, Scrum Methodology, Query Optimization, Message Oriented Middleware, Responsive Web Design, SoapUI, Software Engineering, SQL Stored Procedures, SQL Databases, Systems Integration, Management of Software Versions, Web Services, Enterprise Software Applications, Postman, ReactJS, SOAPAPI, Technical Debt, Build Management, Containerization, Stripe, AngularJS, Solid Principles, Information Technology, Front End Software Development, Restful APIs, Domain Driven Design, Webhooks, Dynatrace, Web Api, Microservices - **Published:** November 5, 2026 - **Apply:** https://www.dice.com/job-detail/bdbd59b9-e8a6-4a51-aa06-54f3c7c30b2f ## About the Role with the potential to convert to full-time. Candidates must reside in the Chicagoland area and able to work onsite 4 days per week., * 10+ years of professional software development experience, primarily in the Microsoft technology stack. * Strong experience with C#, .NET Framework, ASP.NET, ASP.NET Core, MVC, Web API, ADO.NET, Entity Framework, WCF, and REST/SOAP services. * Hands-on experience with payment service providers and gateways, including third-party payment APIs such as Stripe Billing and Subscriptions. * Experience building PCI-aware architectures and securely handling payment and other sensitive data. * Experience with idempotency, retry handling, duplicate transaction prevention, payment webhooks, refunds, reconciliation, and transaction status. * Experience with multi-currency, localization, and country-specific payment differences, plus integrations with ecommerce, Client, and workflow processing systems. * Experience with domain-driven design, microservices, and event-based architectures, including containerization, asynchronous messaging, API versioning, and observability. * Strong SQL Server development skills, including query optimization, stored procedures, triggers, and performance tuning. * Front-end experience with HTML5, CSS, Bootstrap, JavaScript, jQuery, Angular, and React. * Solid grasp of OOP, SOLID principles, design patterns, and clean code, using tools such as Azure DevOps, GitHub, TFS, Visual Studio, Postman, and SoapUI. * Bachelor's degree in Computer Science, IT, Engineering, or a related field preferred (equivalent experience considered); Microsoft, cloud, or DevOps certifications a plus. Nice to Have ยท Experience leading small or onshore/offshore teams, legacy modernization and technical debt reduction, AI-enabled services or workflow automation, Oracle, DB2, or PostgreSQL, and manufacturing or automotive industry experience. ## Description TalentFish is casting a line for a Senior / Lead .NET Developer - Digital Payments & Subscription Commerce. This is a 6-12 month contract opportunity, * Design, develop, test, deploy, and maintain enterprise applications using C#, ASP.NET, ASP.NET Core, MVC, and Web API. * Implement and operationalize subscription capabilities, including pricing plans, purchase and activation, renewals and expirations, upgrades and downgrades, entitlements and service activation, and invoice and transaction history. * Design and build domain-driven, bounded-context solutions using microservices and event-based architectures, including containerization, asynchronous messaging, API versioning and contract management, and distributed tracing. * Build and consume RESTful APIs and web services to integrate with internal systems and external payment and financing partners. * Modernize legacy .NET applications to improve performance, reliability, maintainability, and user experience. * Develop responsive user interfaces using HTML5, CSS, Bootstrap, JavaScript, Angular, and React * Create and optimize SQL queries, stored procedures, triggers, and indexes across SQL Server and other relational databases. * Support customer experience analytics and sales reporting. * Contribute to Agile delivery and CI/CD, including sprint planning, backlog refinement, code reviews, unit testing, and releases through Azure DevOps, GitHub, and TFS. * Provide production support, troubleshoot issues, and lead root-cause analysis and corrective actions. * Collaborate with business users, product owners, QA, infrastructure, and onshore/offshore teams, and mentor developers on best practices.