Senior .NET Developer - Payment Systems & Integrations

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.

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

· 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.

This role requires authorization to work in the U.S. without current or future visa sponsorship. The expected pay rate for this position is $65 - $75 per hour, depending on experience, qualifications, and engagement structure (W2 or C2C). This role also qualifies for comprehensive benefits such as health insurance, 401(k), and paid time off. TalentFish is committed to pay transparency and equal opportunity. The salary range provided is in compliance with applicable state and federal regulations. All offers are contingent upon the completion of a background check, which may include but is not limited to reference checks, education verification, employment verification, drug testing, criminal records checks, and any required certifications or compliance requirements based on the end client’s background check policies and applicable laws.

TalentFish is an employee-owned company pioneering a new realm in talent acquisition. We are redefining IT staffing by evolving AI, video screening, and our unique platform. TalentFish focuses on providing the best employee, consultant, and client experience possible. At TalentFish we are an Equal Opportunity Employer; we embrace and encourage diversity.