Senior Developer

As a Senior Developer at Commercial, you will play a key role in supporting, maintaining, and evolving our core business systems and integrations. Working within the Business Systems team, you will deliver reliable, scalable solutions that support day-to-day operations, improve user experience, and enable business growth.

This is a hands‑on, varied role combining development, database optimisation, and systems integration. You will collaborate closely with stakeholders across the business, contributing to both new initiatives and continuous improvement of existing platforms.

Your responsibilities as a Senior Developer will be:

• Develop, maintain, and enhance business applications, integrations, and internal systems, ensuring solutions are scalable, reliable, and user-focused.
• Work closely with stakeholders to understand requirements, provide technical guidance, and deliver pragmatic solutions aligned to business needs.
• Support and improve existing systems by troubleshooting issues, optimising performance, and enhancing usability and stability.
• Design and deliver system integrations (APIs, middleware, data exchange), ensuring robustness, security, and effective data flow between platforms.
• Take ownership of database performance, including schema design, query optimisation, indexing strategies, and data integrity.
• Manage and support data processes such as imports, exports, transformation, and reconciliation across multiple systems.
• Contribute across the full development lifecycle, including design, development, testing, deployment, and ongoing support.
• Support release management, version control, and deployment processes to ensure controlled and stable system changes.
• Collaborate with internal teams and third‑party suppliers to ensure systems and integrations operate effectively.
• Contribute to continuous improvement by modernising legacy systems and adopting best practice development approaches.
• Explore and implement opportunities to leverage AI and automation technologies to improve system efficiency, data usage and business processes, ensuring solutions are practical, secure and aligned with business needs.

• You will have strong experience in software development using Microsoft technologies (C#, .NET, SQL Server).
• Experience with full Microsoft development stack including WPF and Windows forms. Server integrations such as OData, WCF and other REST APIs.
• Solid understanding of the full development lifecycle, including support and continuous improvement.
• Proven expertise in SQL Server, including performance tuning, database design, and query optimisation.
• Experience with integrations, APIs, middleware (e.g. Connex or similar), and data flows (ETL, transformation, mapping).
• Ability to troubleshoot complex system and data issues across interconnected platforms.
• Good understanding of development best practices, including source control, testing, and structured troubleshooting.
• Exposure to business systems (ERP/CRM), cloud platforms, or web technologies is beneficial.
• Strong problem‑solving mindset with a focus on improving systems and user experience.
• Well organised, able to manage priorities in a fast‑paced environment.
• Confident communicator who works collaboratively and contributes positively to team culture.
• Awareness or interest in AI, automation or emerging technologies, with a practical approach to applying them to real business challenges.

We’re Commercial – a purpose‑driven, people‑first organisation that’s on an exciting journey to reach a £100m annual turnover and beyond. But what really defines us isn’t just the numbers – it’s the people, the culture we’ve built, and the innovative spirit that drives us forward.

As Business Transformation Specialists, we combine original thinking with practical expertise to improve the everyday experiences and outcomes for our clients. Our areas of specialism include Managed IT, Smart Technologies, Digital Workspace, Interiors, Office Supplies, PPE, Facilities, and Workwear.

We’re proud to be an award‑winning employer, having won our category at Sunday Times Best Places to Work 2026, recognised as the Best Place to Work in the Business and Management…