Hybrid Senior .NET Software Engineer

at Paychex

• Job title: Senior .NET Software Engineer
• Job type: Full Time
• Experience level: Senior
• Salary: €4,240 - €6,360 per month
• Degree requirement: Bachelor's Degree
• Tech skills: MySQL, SQL, .NET
• Location requirements: Hybrid, Vilnius, Lithuania

About the role

• Senior Engineer responsible for improving and modernizing a customer facing .NET platform at AccuSourceHR. Leading knowledge transfer and integration with existing workflows and systems.

Responsibilities

• Run structured knowledge transfer covering architecture, module boundaries, data model, integrations, release process, known failure modes, and operational history.
• Produce durable assets: architecture diagrams, runbooks, ADRs, onboarding guides, module maps, and a platform map that new engineers can use.
• Own bug triage and prioritization and ship fixes and small enhancements based on customer feedback and usage signals.
• Reduce recurring issues by addressing root causes and adding regression coverage, not just patching symptoms.
• Keep a clear backlog and release notes so stakeholders know what shipped and why.
• Build and evolve integrations with AccuSourceHR background screening workflows including APIs, identity patterns, data flows, and user journeys.
• Lead a payroll provider integration end to end including data contracts, mapping, error handling, retries, reconciliation, auditability, and observability.
• Plan and execute a staged upgrade toward modern .NET targeting .NET 8 or latest LTS without disrupting customers.
• Build and maintain automated tests across unit, integration, and targeted end to end coverage for critical flows.
• Mentor and onboard future engineers through pairing, code reviews, standards, and documentation.

Requirements

• 7+ years building and maintaining .NET and C# applications across legacy and modern stacks.
• Track record taking over a codebase you did not build and improving it safely over time.
• Strong software engineering fundamentals: clean code, API design, debugging, and performance minded development.
• Strong API and integration skills including auth, versioning, reliability, idempotency, and error handling.
• Strong relational database skills in SQL Server and or MySQL including schema design, migrations, and performance tuning.
• Automation first quality mindset with hands on experience writing and maintaining tests and CI gates.
• Regular responsible use of AI dev tools that improves delivery while protecting IP and sensitive data.
• Strong communication skills with the ability to explain tradeoffs to both technical and non technical audiences.
• Experience writing design docs and leading design reviews for non trivial changes.

Benefits

• Hybrid work setup — up to 3 days remote for flexibility.
• Access to all essential work tools and tech.
• IT equipment for your home office.
• Private health insurance.
• Free parking at our city-center office.
• Snacks, coffee, and good vibes.