Freelance: Integration .NET developerLocation: Brussels (city centre)Start Date: ASAPContract Type: Freelance or Employee (12-month mission, with possible extension)Work Mode: Hybrid (on-site and remote)Mission context & objectivesMy 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 & responsibilitiesDesign, 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 & experienceTechnical skills - mandatory (2 to 5 years)Development with .NET C# (Framework 4.0 and above)Experience with WCF web servicesREST APIs (JSON, Swagger/OpenAPI)XML technologies: XSD, XSLT, XPathMicrosoft development stack: Visual Studio, TFS / VSTS (Azure DevOps)Technical skills - preferredIntegration with batch schedulers (e.g., Control-M)Exposure to Mainframe (z/OS) applicationsExperience with authentication protocols (SAML, OAuth)SQL Server SSISMicrosoft BizTalkDynamics CRMAutomated performance and load testingFunctional experience - mandatory (2 to 5 years)Solid understanding of integration architecture and common integration patternsExperience designing integration workflowsSoft skills - mandatoryAutonomous and proactiveSolution-oriented with a pragmatic mindsetAdaptable and collaborativeStrong communication skillsBusiness experienceMandatory: Proven experience in software/application development using .NET, especially in API and/or batch system integration.Preferred: Experience in the insurance or financial services sectorsLanguage requirements:English - basicFrench - fluentDutch - fluentThe developer must be fluent in either French or Dutch, with at least basic knowledge of the other language.Additional informationDuration: 12 months (extension possible depending on project evolution)Location: Brussels city centre (easy access by public transport)Workload: Full-time