Senior Backend Engineer - AI Product

The OpportunityIf you've worked alongside hardware teams, you know the damage that results from a missed change request or critical context that was never relayed to the right person. Reflow exists to close that gap. We're building the first AI-powered platform purpose-built for hardware product development, one that listens across the tools teams already use, maintains a structured picture of every program, and proactively coordinates across disciplines when things inevitably change.This is a ground-floor opportunity for a hands-on backend engineer to build the core services and AI infrastructure powering this platform, with the support of a parent company leading innovation in engineering and manufacturing.Who We're Looking ForWe're seeking a backend engineer who ships reliable, well-designed systems and takes ownership of the services they build. The ideal candidate has production experience with Python, FastAPI, and PostgreSQL, and is comfortable building everything from REST APIs to background task pipelines to AI agent infrastructure. You should already be using AI coding tools like Cursor, Copilot, or Claude to accelerate your work, with excitement about building the backend that powers the first AI-native platform for complex hardware development.This senior engineer will work alongside our engineering team, AI researchers, and head of product to build the services that turn unstructured inputs (call transcripts, emails, documents, datasheets) into structured engineering artifacts (requirements, project plans, dependencies), orchestrate ambient AI agents for proactive coordination, and serve real-time project intelligence to users. The role is hands-on - you will be coding daily while contributing to system design decisions and helping establish backend engineering best practices as we grow.What You'll DoYour day-to-day responsibilities will include:● Designing and implementing RESTful APIs with OpenAPI specs and auto-generated client SDKs using SQLAlchemy and Postgres● Developing ingestion pipelines using Celery and Redis that connect to tools teams already use (file storage, messaging, email) and extract structured engineering artifacts from unstructured inputs● Building and extending agentic AI workflows using LangChain, LangGraph, and related frameworks for structured data extraction, risk detection, dependency analysis, and proactive team coordination● Integrating LLM APIs (Anthropic Claude, OpenRouter) with streaming (SSE), error handling, and cost optimization● Deploying and operating services on GCP (Cloud Run, Cloud SQL, Memorystore) with Terraform● Writing well-tested, maintainable code and participating in code reviews to establish engineering best practicesTechnical RequirementsMust Have:● 5+ years building production backend systems, with 3+ years in Python● Demonstrated proficiency using AI coding tools (Cursor, Copilot, Claude, etc.) to accelerate development● Strong experience with FastAPI or similar async Python web frameworks● Production experience with PostgreSQL, including schema design, migrations, and query optimization● Hands-on experience with task queues and background processing (Celery, Redis, or similar)● Understanding of API design, authentication patterns (OIDC/JWT), and service architecture● Experience with containerized deployments (Docker) and CI/CD pipelines● Ability to balance rapid iteration with maintainable, well-tested codeHighly Valuable:● Have worked in early-stage 0 to 1 startup environments● Production experience integrating LLM APIs (Anthropic, OpenAI, etc.) and building AI-powered features with agent orchestration frameworks (LangChain, LangGraph, or similar)● Hands-on experience with GCP services (Cloud Run, Cloud SQL, Pub/Sub, Secret Manager) and Infrastructure-as-code experience with Terraform● Experience with data ingestion pipelines and ETL workflows● Background in B2B SaaS platforms, project management tools, or workflow automation products● Understanding of hardware development, engineering workflows, or project management concepts (phases, gates, dependencies)What We OfferReal Impact: The opportunity to build purpose-built tooling for an entire industry that has never had itCustomer Access: Direct exposure to hundreds of real hardware projects annually through Re:Build's engineering and manufacturing companiesTechnical Growth: Hands-on work with cutting-edge AI technologies solving novel technical challengesAutonomy: Backed by Re:Build while operating with startup independenceBenefits: Full health/dental/vision, bonus program, generous 401K, paid time off, annual learning stipendEquity & Growth: Participation in Re:Build's LTIP equity program and opportunity for founder equity in potential spin-outCompensation & LocationLocation: Remote-first, with preference for candidates in Boston, Seattle, Los Angeles, or other cities with Re:Build officesCompensation: Base salary range of $165,000 to $215,000 with performance bonus and long-term incentive pla