Hire the Best .NET Core Developers
in France

I've spent 11+ years building production .NET systems for companies like Canon, PSA, Sodexo, Bolloré and Ceva — and today I'm the senior backend engineer on a multi-tenant B2B SaaS platform in the energy-efficiency sector: four client portals, one modular .NET 9 codebase, running in production under strict quality gates. What I do best: • ASP.NET Core APIs — versioned REST APIs, role-based access control, multi-tenant architecture, FluentValidation, clean vertical-slice structure • Azure data — deep Cosmos DB expertise (partition design, change-feed pipelines, indexing policies, zero-downtime backfills) plus SQL Server, PostgreSQL and EF Core with disciplined migrations • Architecture — modular monoliths and microservices done right: CQRS, DDD, MediatR, Result-based error handling, contracts that never break consumers • Integrations — e-signature providers, rate-limited government APIs, registry exports with strict file formats, RabbitMQ, Redis, SignalR real-time • Full-stack when the job needs it — Angular, React and TypeScript front-ends shipped in production at Sodexo, Bolloré, TUI and Canon • Quality — TDD with xUnit, SonarQube-clean code, benchmark-driven performance work. Every change ships production-ready. How I work: small verified increments, before/after evidence for every performance claim, honest estimates, no surprises. My code survives strict senior review every single day — yours will get the same standard. Available now for full-time or part-time engagements (100% remote, CET) — I reply daily. Send me your API, performance, or migration problem and you'll get a concrete first step within 24 hours.

Looking for a developer who ships reliable, production-ready software without hand-holding? That's exactly what I do. I'm a senior full-stack developer with 8+ years of experience building enterprise-grade web and software solutions across energy, finance, and document management. I specialize in the .NET ecosystem and modern React front-ends, delivering secure REST APIs, microservices, CQRS, Hexagonal (Ports & Adapters) and Clean Architecture, and scalable cloud solutions on Microsoft Azure. I also integrate AI capabilities using OpenAI and Azure OpenAI to automate workflows and add intelligence to business applications. I work autonomously, communicate clearly, and take full ownership from first line of code to final delivery. What I can build for you: REST and Web APIs, microservices, and backend services with C#, .NET / .NET Core, ASP.NET Core, and Entity Framework Core Scalable, maintainable systems using CQRS and Hexagonal (Ports & Adapters) architecture Modern, responsive front-ends with React, Redux, TypeScript, Material UI, DevExtreme, and GrapeCity Secure authentication and authorization with OAuth 2.0, OpenID Connect (OIDC), and Okta Scalable asynchronous architectures using Azure Functions, App Services, Queues, Service Bus, and Storage AI-powered features and automation with OpenAI, Azure OpenAI, and prompt engineering Real-time features with SignalR Robust data layers with SQL Server, PostgreSQL, MySQL, SQLite, and MongoDB CI/CD pipelines with Azure DevOps, YAML Pipelines, and SonarQube for quality and fast delivery Monitoring and observability with Application Insights and Splunk Interactive Power BI dashboards for reporting and decision-making OCR and document-processing automation (PDF extraction, JSON processing) Architecture & best practices: CQRS, Hexagonal (Ports & Adapters), Clean Architecture, SOLID principles, Design Patterns, Microservices, and Agile / Scrum delivery. AI & productivity: OpenAI, Azure OpenAI, Prompt Engineering, GitHub Copilot, Claude, Gemini, Microsoft 365 Copilot — leveraging AI to accelerate development, automation, and delivery. Technical toolbox: Languages: C#, JavaScript, TypeScript, SQL, HTML5, CSS3 Frameworks: .NET Framework, .NET Core, ASP.NET, ASP.NET MVC, ASP.NET Core, Entity Framework (incl. Core), React, Redux UI Libraries: Material UI, DevExtreme, GrapeCity APIs & Security: REST API, OAuth 2.0, OpenID Connect (OIDC), Okta, Azure Key Vault, Swagger Databases: SQL Server, MySQL, PostgreSQL, SQLite, MongoDB, Athena (design, LINQ, Entity Framework) Cloud & DevOps: Microsoft Azure (Functions, App Services, Service Bus, Queues, Storage, Key Vault, Application Insights, Azure OpenAI), AWS S3, Azure DevOps, CI/CD, YAML Pipelines, SonarQube AI: OpenAI, Azure OpenAI, Prompt Engineering, GitHub Copilot Monitoring: Application Insights, Splunk Data & BI: Power BI dashboards, Athena Tools: Visual Studio (2017/2022), VS Code, Git, GitHub, Bitbucket, GitLab, Jira, Trello Why clients choose me: Problem-solving first: every feature is tied to your business goals, not just code for the sake of it. Reliable and autonomous: I plan, deliver, and keep projects moving without constant supervision. Clear communication: regular updates, honest timelines, and no surprises. Long-term mindset: I aim to be the developer you come back to, not a one-off hire. Whether you're starting from scratch or improving an existing platform, I'll help you get it done right. Ready to move your project forward? Click Invite to Job or send me a message, and let's talk about how I can help.

Need to build a new software system from scratch or complete a high-impact architectural feature within a tight timeframe? I specialize in rapid greenfield architecture and targeted 1-month engineering engagements. From enterprise web/desktop applications in .NET and Node.js to real-time interactive systems in C++ and Unreal/Unity, I bring full-stack architecture and hands-on execution to your project. How I Can Help Your Team: New System Development (0 to 1): Designing cloud-native backends (AWS/Azure/GCP) and frontend clients (React, Next.js, React Native) structured for scale. Focused Monthly Engagements: Stepping in for 2–4 weeks to architect and build dedicated modules, API integrations, or desktop engines (.NET Core/WPF). Cross-Platform Engineering: Seamlessly bridging high-level web APIs with low-level C++/engine pipelines. Tech Stack Summary: Cloud (AWS, Azure, GCP, Docker) | Web/Mobile (Node.js, React, Next.js, React Native) | Backend/Desktop (.NET Core, C#, WPF) | Systems (C++, Unity, Unreal) | Scripting (Python, Bash) Let's discuss your timeline and project goals. Send a message to schedule a consultation!

I am a C# .NET developer specialized in Windows desktop applications, POS systems, ERP solutions, and full stack .NET development. Most of my work revolves around building high-performance Windows applications using WPF, WinForms, and .NET Framework, combined with strong backend development using ASP. NET, ASP. NET Core, and REST APIs. I focus on building reliable, scalable, and production-ready software for business-critical systems like POS, ERP, CRM, kiosk applications, and hardware-integrated platforms. My core stack includes C#, .NET Framework, .NET Core, ASP .NET, ASP .NET MVC, Windows App Development, Desktop Application Development, API Integration, RESTful API, SQL, Microsoft SQL Server, PostgreSQL, WPF, WinForms, Windows Services, and Standalone Applications. I build both UI-heavy Windows applications and backend-driven integration systems. I have extensive experience in POS systems including POS terminals, POS software, payment gateway integration, inventory management, order management, and ERP software integration. I work with Point of Sale & Payment Systems, API-based POS sync services, Android POS utilities, kiosk mode applications, offline-first POS applications, and hardware integrations such as printers, cameras, barcode scanners, USB devices, Bluetooth devices, and COM port communication. On the backend side, I design APIs using RESTful architecture, build microservices, and develop secure API integration layers between ERP, CRM, POS, and SaaS platforms. I work with JSON, authentication, JWT, OAuth, logging, error handling, offline synchronization, and real-time integrations. My systems are designed to be cloud-ready and scalable using Azure, CI/CD pipelines, and containerized deployments when required. For Windows desktop development, I build professional WPF and WinForms applications including kiosk platforms, shell replacement systems, device control utilities, screen recording software, clipboard tools, document automation, trading applications, charting platforms, and reporting tools. I follow clean architecture and MVVM for WPF projects and deliver stable EXE builds with application installers. I also build hybrid systems using WebView2, Blazor, and React to connect desktop applications with modern web platforms. This allows POS back offices, admin panels, dashboards, and reporting systems to be built as full-stack products using .NET and modern frontend frameworks. Databases are a major part of my work. I design schemas, write optimized queries, stored procedures, and integration layers using Microsoft SQL Server, PostgreSQL, SQLite, MongoDB, and structured reporting systems like SSRS. I build reporting dashboards, financial reports, inventory analytics, and trading reports. I work on enterprise-level products such as ERP systems, CRM platforms, POS infrastructure, SaaS applications, microservice architectures, and financial platforms. I also build AI-powered features including LLM integration, AI model integration, Python execution inside .NET, analytics insights generation, and automation workflows.

I’m a Full Stack Software Engineer with over 8 years of hands-on experience delivering enterprise-grade, secure, and scalable web and mobile solutions. I specialize in .NET (Core, 6, 7, 8), Angular, Azure, DevOps pipelines, SQL Server, PostgreSQL, and Flutter for mobile. I’ve built and delivered systems for leading banks and multinational corporations, including: 🏦 CIH Bank (Morocco) – financial service applications, secure APIs, and automation systems. 🏦 Société Générale (France) – scalable backend systems and microservices for financial operations. 🏦 AXA (France) – insurance automation, data integration, and cloud modernization. 🏦 Natixis (France) – internal banking tools and data management platforms. 🚗 Nissan (UK) – production and logistics-related applications. I’ve also worked with multiple startups and B2C clients, helping them go from idea to live MVPs in record time. ⚙️ My Core Technical Stack 🔹 Backend Development .NET 6 / 7 / 8, ASP.NET Core, C#, Entity Framework Core RESTful APIs, gRPC, Microservices, WebSockets Domain-Driven Design (DDD), CQRS, Clean Architecture Authentication & Authorization (JWT, OAuth2, Azure AD) Background services, scheduled jobs, and event-driven systems 🔹 Frontend Development Angular (v10+), TypeScript, RxJS, TailwindCSS, Material Design Reactive state management and component-driven architecture REST API integration, modular routing, lazy loading, performance optimization 🔹 Cloud & DevOps Azure App Services, Azure Functions, Azure SQL, Blob Storage Azure DevOps CI/CD Pipelines, GitHub Actions, Docker, Kubernetes Infrastructure as Code (IaC), ARM templates, Terraform basics Application monitoring, logging, and deployment automation 🔹 Databases SQL Server, PostgreSQL, Azure SQL Database design, optimization, indexing, complex queries, stored procedures Data migrations, backup & restore strategies, replication 🔹 Mobile Development Flutter cross-platform development (iOS & Android) Riverpod state management, in-app purchases, Firebase integration Subscription systems, onboarding workflows, offline support with SQLite 🚀 My Work Philosophy – Ship Fast, Ship Smart I focus on delivering results quickly and efficiently without compromising code quality or scalability. I apply a "Ship Fast" methodology for MVPs: short development cycles, fast iterations, and production-ready code within weeks. For larger projects, I lead with Agile/Scrum principles: Sprint planning, backlog prioritization, and roadmap management Team coordination (devs, QA, designers, PMs) Code reviews, CI/CD automation, and continuous improvement Whether you need a solo full-stack developer or a technical lead to guide your team through an enterprise project, I can help you achieve predictable, scalable delivery. 🧠 Why Clients Hire Me Bank-Grade Reliability: Years of experience with financial institutions where security, compliance, and uptime matter most. Technical Depth + Management Experience: I can code, architect, and manage — ensuring the entire project stays on track. MVP to Scale: I’ve helped startups and established businesses launch new digital products in record time. Clean, Maintainable Code: SOLID principles, modular architecture, and best DevOps practices built into every delivery. End-to-End Ownership: From planning, design, and development to deployment and maintenance — I handle it all. 💬 What You Can Expect When Working With Me ✅ Transparent communication — daily or weekly updates, clear timelines, and total visibility. ✅ Fast and reliable delivery — I don’t just promise, I deliver production-ready results. ✅ Long-term mindset — I build systems designed to evolve, scale, and perform over time. ✅ Collaboration — I can work independently or manage and mentor a small development team. ✅ Full technical documentation and deployment guidance provided at every stage. 🧩 Industries I’ve Worked In Banking & Financial Services Insurance Automotive Healthcare SaaS & Subscription-based Apps Education & Learning Platforms Retail & B2C Mobile Solutions 🧰 Key Strengths End-to-end product development (Web + Mobile + Cloud) Scalable architecture for high-traffic systems Cross-platform development (Flutter + Web APIs) Azure cloud deployment, monitoring, and cost optimization SQL performance tuning and data consistency Leading teams through modern Agile and DevOps processes 🌍 Let’s Build Something Impactful If you’re looking for a reliable full-stack engineer who can design, implement, and deploy robust systems — and who understands what quality and delivery really mean — I’d love to collaborate. I can: Architect and build secure .NET & Angular platforms Integrate complex APIs and databases Launch Flutter mobile apps with subscription models Set up CI/CD pipelines and cloud infrastructure Manage a development team and ensure on-time delivery 📩 Let’s discuss your project. Whether it’s a large enterprise platform or a startup MVP

Hi, I'm Guillaume, from France. With over 13 years of experience in IT in various IT consulting companies specializing in Microsoft technologies, I have built up a robust and reliable technical background. I have worked alone and in a team, with CI/CD best practice tools and code reviews. I love building dekstop and mobile application, beautiful UI and seemless UX. I published several application on Store (iOS, Android & Microsoft) by my own, and for customer. Let discuss about your project :)