Senior Software Engineer (Full-Stack .NET)

Paychex is reimagining how businesses manage their workforce by bringing payroll, HR, benefits, and advisory services together into a single connected HCM platform. As Paychex and Paycor come together, we're combining innovative technology, data-driven insights, AI, and human expertise to help organizations work smarter, support their people, and achieve better business outcomes. This is an exciting time to join our team as we continue to invest in innovation, simplify client experiences, and shape the future of work. At Paychex, you'll have the opportunity to grow your career, make a meaningful impact, and be part of something bigger as One Paychex.
Responsibilities

• Design, develop, and deliver scalable software solutions that support business needs.
• Build and operate services in Azure, applying the security and data-protection practices required for payroll and HR data.
• Support production systems, troubleshoot technical issues using telemetry and tracing, and help ensure system stability.
• Build and evolve the agent tooling and integrations — MCP servers, tool registries, external agent connections — that let WISE work across products and platforms.
• Participate in architecture and technical design discussions, contributing to system improvements.
• Improve testing, deployment, and monitoring processes to enhance software quality and reliability.
• Mentor engineers, share technical knowledge, and help remove technical roadblocks to keep projects moving forward.
• Perform code reviews and promote engineering best practices across the team.

Qualifications

• Strong experience with .NET/C# technologies.
• 5+ years of hands-on experience in full lifecycle software development.
• Good knowledge of JavaScript and React.
• Hands-on experience building and running services on Azure (App Service, Functions, API Management, or equivalent).
• Strong production-debugging instincts — able to reconstruct what actually happened from telemetry
• Experience designing and developing microservices-based architectures.
• Experience with REST API design and with authentication/authorization (OAuth 2.0 / OIDC).
• Experience with CI/CD pipelines (e.g., GitHub Actions) and automated quality gates.
• Experience creating and maintaining automated tests.
• Experience with cloud data stores — Cosmos DB or other NoSQL/document databases — and working knowledge of MS SQL, including database design and optimization.

• Nice to have:
• Experience with LLM or agent frameworks (e.g., LangChain, Semantic Kernel / Microsoft Agent Framework) and agent interoperability protocols (MCP, A2A), prompt and tool design, retrieval-augmented generation, or evaluating AI systems.
• Exposure to HR, payroll, or other regulated domains.
• Familiarity with event-driven architectures, message queues, and containers.

What's in it for you?

• A flexible work philosophy
• Company paid private health insurance
• Company paid life and disability insurance
• Paid leave for illness, birth parents, non-birth parents, elder caregivers, marriage, adoption of a child and bereavement
• Inclusive and accessible Employee Assistance Program (EAP) to help with everyday challenges
• Christmas and Easter bonuses
• Opportunity for strengthening expertise and skills through Paychex’s learning platform, including lessons in English

Not sure if you meet every requirement?

At Paychex, we know that great talent comes in many forms. If you're passionate about the role but don't check every box, we still encourage you to apply. You might be the right fit - either for this position or another opportunity with us.

Paychex is an equal opportunity employer. We are committed to fostering a respectful and inclusive workplace where all individuals are treated fairly and evaluated based on their qualifications, experience, and merit. We comply with all applicable federal, state, and local laws prohibiting discrimination in employment.