SECTION I · THE BRIEF
Brief #42265Updated 21 AUG 2026SAN FRANCISCO, CAYcY COMBINATOR
Employbl Company Profile

Founding AI Engineer

Semble AI automates fire and life-safety system design using AI to turn manual workflows into code-compliant processes.

Location
San Francisco, CA
Company size
2–10
Posted
2w ago
Via
Yc
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  • 01Comp band & equity packageLocked
  • 02Seniority & experience requirementsLocked
  • 03Interview process & rubricLocked
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  • 05Growth trajectory in this roleLocked
  • 06Offer & decision timelineLocked
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Job listing · Updated 21 AUG 2026

Founding AI Engineer

Semble AI· San Francisco, CA, USView company profile

Job title
Founding AI Engineer
Job location
San Francisco, CA, US
Job listing URL
https://www.ycombinator.com/companies/semble/jobs/d4YUIn2-founding-ai-engineer
Job description
We're building AI agents that design building-systems (fire, HVAC, plumbing, security) instantly and code-compliantly. The $600B building-system integration industry still runs on spreadsheets and manual drawings, even as building codes rapidly evolve and become more localized. It’s a massive blind spot for the tech world. We are transforming building-system design from a months-long, error-prone process into an instant, automated workflow. Semble AI is becoming the industry standard for top quality commercial building design. ### **What you’ll work on** 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. ### **Our tech** * **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 ### **You might be a great fit if you** * 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 ### **Why join us** * 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
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Where this role is based

San Francisco, CA

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Semble AI headquarters

San Francisco, CA

Company size

2–10 employees

Founded

2025

Total raised

$500,000

View company profile ↗

Funding rounds

Investors

Y Combinator