Mid Full-Stack Engineer (Python/FastAPI/React)

We're looking for a mid-level full stack engineer to build features end to end across a Python/FastAPI backend and a React/TypeScript frontend. A large share of the work involves LLM-powered product features: an AI agent that calls tools to read and write real project data, and pipelines that pull structured data out of messy documents. Location:LATAM 100% Remote. Working hours are based on the US Central Time Zone. Minimum 6-hour overlap. About us: Abstra is a fast-growing, Nearshore Tech Talent services company, providing top Latin American tech talent to U.S. companies and beyond. Founded by U.S.-bred engineers with over 15 years of experience, Abstra specializes in sourcing skilled professionals across a wide range of technologies to meet our clients’ needs, driving innovation and efficiency. Key Responsibilities: • Build and ship full-stack features. • Create fast proof-of-concept work for demos and client feedback. • Extend the AI agent: add and maintain tools with typed input and output schemas, refine system prompts, and keep model outputs grounded in data from the database. • Measure LLM behavior with evaluation suites and use the results to guide changes to prompts, tools and models. Changes should be backed by evals, not hunches. • Improve document extraction and classification pipelines for PDFs, Excel, Word, and CSV files, including the LLM-assisted steps. • Build data-heavy UI: tables, charts, maps and streaming chat interfaces. • Write tests at every layer (pyt