.NET C# Developer for Web Application

We are looking for a specialized .NET / .NET Core, ASP.NET Core, and C# expert (freelance or agency) to develop the backend of a conversational chatbot. This application will serve as the bridge to our AI orchestration layer built with LiteLLM and LangGraph (Python ecosystem). (.NET 10 for the application). We need a developer who can seamlessly create and connect the chatbot to our AI solution. the developer take care of the application, we take care of the AI orchestration. The selected contractor will be responsible for implementing the following specific features: Architecture Setup: Initialize the .NET 10 architecture and base controllers. Health Check: Create the SystemController and the /health route. Streaming Infrastructure: Setup the SSE (Server-Sent Events) middleware and handle custom HTTP headers. Error Handling: Implement robust upstream error handling with specific error codes: BUDGET_EXCEEDED, CONTEXT_TOO_LARGE, UPSTREAM_TIMEOUT, INVALID_REQUEST. Payload Structuring: Format strongly-typed SSE payloads (meta, content, final). Data Persistence: Define EF Core entities and configure JSONB storage (for flexible LLM contexts/metadata). History Management APIs: Develop the GET /conversations route (list user history). Develop the GET /conversations/id/messages route (fetch full chat history). File Management: Create middleware for attachment extraction supporting multipart/form-data. Audio Features: Create the SpeechController and the /speech/transcribe route. Advanced Chat Controls: Implement clean interruption routes (to stop LLM generation mid-flight) and message editing capabilities. We planned 5 day work maximum on this project based on our experience. We will select the candidate who is available, can deliver and work in a few weeks, ideally that have already developped .net chatbots.