The Role
Lead development of production AI systems for building-system design including vision pipelines for PDF/CAD parsing, LLM+RAG workflows for code-compliant designs, AI agent orchestration, and full-stack features across a Typescript/React/Node/Postgres platform. Significant ownership and technical direction at an early-stage startup.
Summary Generated by Built In
About Semble AI
Semble AI builds AI agents that design building-systems (fire, HVAC, plumbing, and security). Construction companies use Semble to replace weeks of manual design work with instant, code-compliant system layouts and bills of materials.
The $600B building-system integration industry still runs on spreadsheets and hand-drawn markups, even as building codes evolve rapidly and grow more localized. It’s one of the largest blind spots in construction tech, and we’re fixing it.
Jonathan and Ethan met studying computer science at Stanford. Jonathan worked at Convergint, one of the world’s largest building-system integrators, to learn the industry from the inside. Ethan’s motivation is personal: his home burned down in 2017 due to a faulty fire system.
We’re building the platform that will become the industry standard for construction-system design, and we’re looking for people who want to build foundational AI products that touch every building on the planet.
As a founding engineer, you’ll work directly with the founders to own and build systems such as:
- Vision pipelines that segment rooms, walls, and architectural elements from noisy PDFs/CAD files
- LLM + RAG workflows that interpret building codes and produce compliant designs
- Full-stack features across our React/Node/Postgres platform
You’ll have massive ownership and help set the technical direction of a company in a market that’s about to undergo a once-in-a-generation transition.
- Typescript / React / Node / Express / PostgreSQL
- Python (PyTorch, NumPy, etc.)
- Vision models: object detection, instance + semantic segmentation
- AI Agents: multi-agent reasoning, workflow orchestration, MCP
- RAG pipelines: vector DBs, embeddings, chunking strategies
- Have strong experience in ML (vision AND LLMs), backend, building AI agents, and full-stack engineering
- Thrive in fast-moving environments and love shipping end-to-end
- Care about building reliable, production-grade AI systems
- Want to be early at a YC startup where your work directly defines the company’s trajectory
- You’ll work directly with the founding team (YC F25)
- Ship real AI systems into production for companies across the U.S.
- Own major pieces of the product and architecture
- Help shape the engineering culture from day zero
- Build something that will become the industry standard for top quality commercial building design
The base pay range for this role is $150,000 – $250,000 per year.
Skills Required
- Strong experience in machine learning (vision and LLMs)
- Experience building AI agents and multi-agent reasoning/workflow orchestration
- Backend and full-stack engineering experience (Typescript, React, Node, Express, PostgreSQL)
- Python experience with PyTorch and NumPy
- Experience with vision models: object detection, instance and semantic segmentation
- Experience building RAG pipelines, vector DBs, embeddings, and chunking strategies
- Ability to ship production-grade, reliable AI systems and operate in fast-moving startup environments
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The Company
What We Do
Semble AI provides AI-powered workflow automation for construction back-offices, specializing in the design of building systems such as fire, HVAC, plumbing, and security. By deploying custom AI agents trained on a business's specific operations, Semble transforms manual, repetitive processes—including scheduling, coordination, and project handoffs—into efficient, code-compliant workflows, significantly reducing the time required for commercial and residential project design.
