Freelance: Integration .NET developer Location: Brussels (city centre) Start Date: ASAP Contract Type: Freelance or Employee (12-month mission, with possible extension) Work Mode: Hybrid (on-site and remote) Mission context & objectives My client is seeking an Integration .NET Developer to support the digital transformation of its internal systems. The candidat will begin the mission within the central integration team, learning and applying the company's development standards and integration best practices. Once onboarded, they will be assigned to a business IT department to support ongoing projects and help strengthen the .NET integration expertise within the team. Role & responsibilities Design, implement and test new software components, enhancements, and fixes. Work on integration solutions involving internal systems, external packages, and cross-technology platforms. Write clear and structured documentation. Participate in troubleshooting and incident resolution. Coordinate deployments to test, staging, and production environments via the company's release processes. Collaborate with functional analysts, business stakeholders, and infrastructure teams. Required skills & experience Technical skills - mandatory (2 to 5 years) Development with .NET C# (Framework 4.0 and above) Experience with WCF web services REST APIs (JSON, Swagger/OpenAPI) XML technologies: XSD, XSLT, XPath Microsoft development stack: Visual Studio, TFS / VSTS (Azure DevOps) Technical skills - preferred Integration with batch schedulers (e.g., Control-M) Exposure to Mainframe (z/OS) applications Experience with authentication protocols (SAML, OAuth) SQL Server SSIS Microsoft BizTalk Dynamics CRM Automated performance and load testing Functional experience - mandatory (2 to 5 years) Solid understanding of integration architecture and common integration patterns Experience designing integration workflows Soft skills - mandatory Autonomous and proactive Solution-oriented with a pragmatic mindset Adaptable and collaborative Strong communication skills Business experience Mandatory: Proven experience in software/application development using .NET, especially in API and/or batch system integration. Preferred: Experience in the insurance or financial services sectors Language requirements: English - basic French - fluent Dutch - fluent The developer must be fluent in either French or Dutch, with at least basic knowledge of the other language. Additional information Duration: 12 months (extension possible depending on project evolution) Location: Brussels city centre (easy access by public transport) Workload: Full-time