Sanvir K.

I design and build multi-tenant SaaS platforms on .NET, ASP.NET Core, C# and Azure, and I modernize legacy .NET applications and migrate them to Azure. With 15+ years of experience, I deliver multi-tenant platforms, CRM and workflow systems, business APIs and cloud applications for production use. I work with companies that need more than isolated coding tasks—teams that need a senior engineer who can understand the business workflow, choose a maintainable architecture, and deliver reliable software through production. Recent work includes a multi-tenant call center management SaaS (Twilio, role-based access, real-time dashboards), a dispatch management platform for logistics operations, a multi-channel sales system integrating 30+ marketplaces including Amazon and eBay, and a multi-tenant scheduling SaaS where I cut data sync time from hours to about 4-5 minutes. What I build - Multi-tenant SaaS platforms. - CRM, ERP, and business management systems. - Workflow and approval automation. - Customer portals and admin dashboards. - Enterprise web applications and APIs. - Booking, scheduling, and operations platforms. - Real-time applications and background processing. - AI-enabled business applications. - Legacy .NET modernization and migrations. - Cloud-native applications on Microsoft Azure. What I can help you with • New product architecture and development. • ASP.NET MVC or legacy .NET modernization. • ASP.NET Core and .NET 8 application development. • REST, GraphQL, gRPC, and SOAP APIs. • Third-party API and payment integrations. • Multi-tenant architecture and role-based access control. • Authentication with JWT, OAuth, OpenID Connect, and SSO. • Database design, query optimization, and performance improvement. • Azure deployment, Docker, CI/CD, and production support. Core technology stack Backend: C#, .NET, ASP.NET Core, ASP.NET MVC, Entity Framework Core, Web API. Frontend: Angular, React, TypeScript, JavaScript. Cloud and DevOps: Microsoft Azure, AWS, Docker, Kubernetes, Azure DevOps, CI/CD. Data: SQL Server, PostgreSQL, Redis, Entity Framework. Architecture: Clean Architecture, DDD, microservices, event-driven systems, multi-tenant SaaS. Integrations: REST, GraphQL, gRPC, SignalR, Stripe, Twilio, SendGrid, QuickBooks, payment and business APIs. Why clients hire me • I work across architecture, backend, frontend, cloud, integrations, and delivery. • I can improve an existing system without forcing an unnecessary rewrite. • I identify technical risks early, especially around scalability, security, data, and maintainability. • I communicate clearly about trade-offs, priorities, and delivery scope. • I take ownership of production quality—not just individual features. I’m a good fit for: • SaaS founders building or scaling a product. • Businesses replacing spreadsheets and manual workflows. • Companies modernizing legacy .NET applications. • Product teams that need a senior .NET engineer or technical lead. • Teams that need API and third-party integrations built or fixed. Send me your product requirements, current architecture, or the problem you need solved. I can help define the implementation path and deliver the software.