Senior Software Engineer (Mainframe)

Senior Software Engineer (Mainframe) – Bank – Belgium/France

Daily rate: €600 - €800

Duration: 12 months

Start: ASAP

My client is looking for a Senior Mainframe Software Engineer / Technical Lead to join a high-performing engineering team responsible for the design, development, modernisation, and support of critical enterprise systems.

This role combines deep technical expertise with leadership responsibilities, requiring someone who can architect scalable solutions, drive technical excellence, mentor engineers, and collaborate across multiple teams to deliver high-quality software solutions. You will play a key role in modernising legacy platforms, improving engineering practices, and ensuring the stability and performance of business-critical applications. A 12 month freelance contract, candidates should be based in Belgium or France and 8 days a month on site is mandatory.

Role:

• Drive the design, architecture, and implementation of scalable solutions, owning complex features and collaborating across teams to deliver robust, scalable systems.
• Mentor engineers, supporting complex problem-solving and team growth.
• Lead ideation workshops, shaping high‑impact ideas to improve product functionality and user experience.
• Drive definition, estimation, and validation of complex multi-team requirements.
• Solve dependencies, improve planning accuracy, and ensure predictable, high‑quality delivery through strong technical judgment and collaboration.
• Maintain production stability by leading investigations, delivering durable fixes, and proactively resolving systemic issues.
• Promote and refine coding standards and best practices aligned with system requirements and business processes.
• Support continuous improvement initiatives to enhance code quality and engineering effectiveness.
• Contribute to the adoption of company modernization initiatives.

Requirements:

• Solid experience as a software engineer.
• Deep understanding of software-related system architectures and designs.
• Hands‑on experience with tools such as:
• File Manager, SPUFI, QMF, Fault Analyzer, Git, CI/CD pipelines, APIs, MQ Series, Linux, SOAP UI, Z/OS Connect and enterprise application monitoring and troubleshooting tools.
• Solid experience with programming languages such as:
• PL/1, SQL, DB2 Stored Procedures, PL/SQL, JCL and CICS development (including CICS Web Services).
• Hands-on Experience with Databases: Mainframe DB2, VSAM, and relational database technologies.
• Solid command of advanced Git workflows, testing and quality standards, ability to independently diagnose complex issues via logs/monitoring, and proactively apply secure coding and dependency best practices.
• Demonstrated growth in technical expertise, cross‑functional collaboration, and ownership of areas such as cloud migration, AI integration, automation, Infrastructure as Code, CI/CD, and engineering best practices.
• Solid knowledge of solution development and core design principles.
• Proven ability to analyse business requirements, anticipate technical impact, and guide scalable solution design, while working autonomously and taking ownership of end-to-end outcomes.
• Solid knowledge of Agile methodologies.
• Strong command of English, both spoken and written.

What makes you stand out:

• Experience in Credit Management, Payments, Treasury, or Banking Operations.
• Knowledge of Mainframe modernization and migration initiatives, including integration between legacy and modern platforms
• Background in Machine Learning, Data Science, or Generative AI.
• Demonstrated leadership, interpersonal capabilities and impact mindset.