Full-Stack SaaS Developer Needed for Confidential Pilot Product (CSV + Dashboard + Backend)

I'm looking for an experienced Full-Stack SaaS Developer to build the next iteration of an early-stage B2B SaaS pilot product. The product is a data-driven business application that processes structured business data uploaded through CSV files and presents analytical, forecasting and AI-assisted insights through a web application. The product is already substantially defined, and I'm looking for a developer who can help turn the next iteration into a robust, scalable product. Product-specific details and the existing codebase will be shared with the selected developer. This is not a simple website or UI project. What the product involves At a high level, the application includes: Secure user authentication Customer-specific data environments CSV upload and processing Data validation and normalization Database storage Backend APIs Business and financial calculations Historical data analysis Forecasting Analytical dashboards Drill-down/detail views AI/LLM integration AI-generated explanations based on structured business data Interactive investigation workflows Basic administration functionality The goal is to build a working SaaS product suitable for early pilot customers, not a throwaway prototype. Technical Requirements Strong experience with: Next.js React TypeScript Backend/API development SQL/database design CSV/data ingestion Data transformation SaaS architecture Multi-tenant applications Authentication and authorization LLM/API integrations Vercel or comparable cloud deployment Experience building data-heavy SaaS, BI, analytics, financial or operational applications is strongly preferred. AI Component The product includes an AI layer that works with structured application data. The developer should understand: LLM API integration Passing structured/contextual data to models Generating reliable responses from business data Maintaining consistency between application calculations and AI output Building follow-up/investigation workflows around AI This is not a generic chatbot project. Development Approach The first engagement will focus on Iteration 1. The selected developer will receive: Detailed product requirements Technical requirements UI/design direction Business logic Existing implementation/codebase Specific iteration milestones The product requirements are substantially defined, but this is still an early-stage product, so the developer needs to be comfortable making sound engineering decisions as requirements evolve. What I'm Looking For I'm looking for an individual senior developer, not an agency salesperson. You should be able to: Understand business requirements Translate them into technical architecture Work independently Write clean, maintainable code Think about scalability from the beginning Identify technical issues before they become problems Communicate clearly Take ownership of the implementation Experience with FP&A, finance, RevOps, CRM, BI, forecasting or business analytics is a major plus. When Applying Please include: 2–3 relevant SaaS/data-heavy applications you personally built What you personally developed on each project Your Next.js/React/TypeScript experience Your backend/database experience Your experience with LLM APIs Your experience with CSV/data ingestion Your hourly rate Your availability over the next 4–6 weeks Generic agency proposals will be ignored.