Back-End Developer – Sitecore XM 10.2 (Security & Stability)

Context

The Belgian, German and wider European energy landscape is undergoing rapid transformation. Our client is a European transmission system operator that plays a critical role in ensuring a reliable, sustainable and secure electricity supply across multiple countries.

Working alongside other contingent workers and internal teams, you will contribute to building a future-proof, green and reliable energy infrastructure that supports economic growth while reducing environmental impact. The organization strongly values diversity and inclusion, believing that an inclusive work environment drives innovation, creativity and better results.

Service Description

The Digital Workplace – Communication domain delivers tools and platforms that enable seamless internal and external communication. This includes corporate websites and employee-facing portals used across multiple departments within the organization.

Purpose of the Role

As a Back-End Developer with a strong focus on Sitecore XM 10.2 security and stability, you will strengthen the resilience of the client’s digital platforms. Your work will ensure that websites and communication systems are secure, performant and stable, while supporting the transition toward Sitecore XM Cloud.

You will work closely with architects, DevOps engineers and IT Security teams to implement secure development practices, optimize performance and ensure compliance with internal security policies.

Key Responsibilities

Maintain and stabilize the existing Sitecore XM 10.2 platform until cutover to XM Cloud
Implement and continuously improve secure development practices for Sitecore and .NET
Perform vulnerability scanning, patching and remediation for Sitecore instances, pipelines and modules
Conduct regular code reviews with a focus on performance, scalability and security
Optimize platform performance through caching, database tuning and CDN/WAF improvements
Enhance monitoring, logging and alerting (e.g. Application Insights, Azure Monitor or similar tools)
Participate in the definition and adoption of SLA/OLA, incident and change management processes
Ensure coexistence readiness with XM Cloud, including content parity validation and cache/purge coordination
Support the feature-freeze policy on legacy XM 10.2 (security, compliance and stability fixes only unless approved)
Stay up to date with web security standards, Sitecore patches and .NET frameworks
Document all technical and security changes in line with governance and audit requirements
Support the project team currently working on the migration to Sitecore XM Cloud

Requirements

Bachelor’s or Master’s degree in Computer Science, Information Technology, or equivalent experience
Minimum 5 years of recent experience in Sitecore back-end development with a focus on security and performance
5+ years professional experience in C#/.NET back-end development
Proven experience with Sitecore XM 10.2 (installation, pipelines, configuration, patching and optimization)
Strong command of English; knowledge of Dutch and/or French is an advantage
Knowledge of Sitecore XM Cloud is a plus
Strong understanding of web application security principles (OWASP, secure headers, encryption, CSRF, XSS)
Experience with DevOps and CI/CD pipelines for Sitecore (Azure DevOps, GitHub Actions or similar)
Experience working with Sitecore XM 10.2 on-premises, including manual deployment procedures
Hands-on experience with SQL Server performance tuning and Sitecore content delivery scaling
Experience with WAF/CDN configurations in combination with on-premises Sitecore XM 10.2 (e.g. F5, Azure Front Door, Cloudflare)
Practical knowledge of application observability tools (Application Insights, Seq, Kibana or similar)
Strong collaboration skills and ability to work effectively with architects, DevOps and security teams
Excellent documentation and communication skills in English
Understanding of TOGAF 10.2 and strong document-writing capabilities

Additional Information
Work regime: Full-time
Location: Brussels
Onsite presence: 2 days per week on-site (default requirement)

Bac-End Developer - Sitecore XM