Senior / Lead C# Developer

avacone Iberia; Mulhouse; On-site; EUR 55,000 - 75,000; Full time

Job summary

A prominent IT services company in Mulhouse, France, is seeking an experienced Senior / Lead C# Developer to design and deliver enterprise-grade software solutions for a major banking client. This role combines hands-on development with technical leadership in a collaborative environment. Ideal candidates will have strong experience in C# and the .NET ecosystem, along with a proven track record in managing delivery and stakeholder engagements. This position requires on-site work at the client location and offers an exciting opportunity to contribute to impactful projects.

Qualifications

• Strong commercial experience with C# and the .NET ecosystem.
• Proven experience in a Senior and/or Lead engineering role.
• Solid understanding of enterprise application architecture.
• Strong knowledge of relational databases and SQL performance fundamentals.

Responsibilities

• Design, develop, and maintain secure, scalable applications using C# and .NET.
• Act as technical lead for development activities on client engagements.
• Take ownership of solution architecture, code quality, and technical standards.
• Lead and mentor developers through code reviews and best practices.
• Ensure solutions comply with client security, risk, and regulatory requirements.

Skills

C#

.NET ecosystem

RESTful APIs

SQL Server

Oracle

PostgreSQL

Azure

Collaboration

Stakeholder management

Job description

We are an established IT services company working closely with clients in the banking and financial services sector. We are looking for a Senior / Lead C# Developer to lead the design and delivery of enterprise‑grade software solutions for a major banking client. This role combines hands‑on development with technical leadership, operating within a regulated banking environment while remaining part of a professional, delivery‑focused IT organization.

Location: This role is based in Mulhouse and St. Louis, France, and requires working on‑site at the client location as part of a collaborative delivery team.

Key Responsibilities

• Design, develop, and maintain secure, scalable applications using C# and .NET (including .NET Core / .NET 6+)
• Act as technical lead for development activities on banking client engagements
• Take ownership of solution architecture, code quality, and technical standards across the delivery lifecycle
• Lead and mentor developers through code reviews, coaching, and the promotion of best practices
• Ensure solutions comply with client security, risk, and regulatory requirements
• Work closely with client stakeholders, product owners, and internal delivery teams to define and deliver solutions
• Contribute to technical estimations, planning, and delivery commitments
• Identify, communicate, and mitigate technical risks in a client‑facing environment
• Support production readiness through strong documentation, testing discipline, and operational awareness

Required Skills & Experience

• Strong commercial experience with C# and the .NET ecosystem
• Proven experience in a Senior and/or Lead engineering role (team leadership, ownership of delivery)
• Solid understanding of enterprise application architecture, OO design principles, and common design patterns
• Hands‑on experience building and consuming RESTful APIs
• Strong knowledge of relational databases (e.g., SQL Server, Oracle, PostgreSQL) and SQL performance fundamentals
• Experience with cloud and hybrid environments (Azure preferred)
• Familiarity with security, compliance, and risk considerations in banking or other regulated industries
• Comfortable working in a client‑facing role with high expectations on quality, communication, and delivery
• Strong collaboration and stakeholder‑management skills in multi‑team environments

Nice to Have

• Previous experience working for an IT consultancy or systems integrator
• Exposure to banking platforms, core banking systems, or financial data flows
• Experience with microservices, messaging systems, and/or event‑driven architectures
• Knowledge of CI/CD pipelines, DevSecOps, and automated testing practices
• Experience working in agile delivery models within enterprise environments (Scrum/Kanban)