Mayank S.

I help software companies fix, scale and extend the systems their business runs on, and build AI into them in a way that holds up in production. Recent work: ✔️ Re-architected a payments platform that was failing at ~100 concurrent users into one reliably handling 10,000+ transactions every 15 minutes. ✔️ Built an n8n + Claude API chatbot that lets a SaaS sales team quickly answer manufacturers' questions about how architects engage with their products, delivered in each manufacturer's preferred format. ✔️ Built AgentRAG, a multi-tenant agentic RAG platform (open source): hybrid pgvector + full-text retrieval with RRF fusion, cross-encoder re-ranking, Postgres row-level security for tenant isolation, and an evaluation harness for retrieval quality. ✔️ Designed a Claude Code pipeline (Opus orchestrator, parallel Sonnet sub-agents, a custom MCP server) that takes tickets to merged PRs on a multi-tenant .NET SaaS platform, cutting feature delivery time by ~40%. Over 15 years I've designed, scaled and modernized distributed SaaS systems across fintech, insurance, healthcare and enterprise domains, where reliability, security and handling sensitive data correctly are non-negotiable. Core stack: C#/.NET Core, ASP.NET Web API, Azure (App Services, Service Bus, Functions, Key Vault), SQL Server and PostgreSQL, DDD, microservices. AI stack: OpenAI and Claude APIs, RAG (embeddings, pgvector, hybrid search, re-ranking, evaluation), agentic workflows, MCP, n8n. Clients bring me in for: ✔️ A system that breaks, slows down or fails under load, and needs someone senior to diagnose and fix it properly. ✔️ A new backend or API that has to be built right the first time, with security and scale designed in. ✔️ AI features (RAG search, LLM integrations, agents, automation) that must be secure, multi-tenant, observable and cost-controlled, not fragile demos. Microsoft Certified: Azure AI Apps and Agents Developer Associate. I take on a small number of engagements at a time so each client gets senior attention. Expert-Vetted, 100% Job Success, 10,000+ hours on Upwork. If you have a system or an AI feature that needs to work properly, let's talk.