Founding Engineer (Full-stack)

Role: Founding Full Stack Engineer

Location: In-person, SF

Stack: Next.js, TypeScript, FastAPI, PostgreSQL, AWS (ECS, Fargate), LLM APIs

Frontend Platform

What You’ll Work On

• Architect and ship core product surfaces with Next.js Typescript
• Design and implement high quality user experiences for complex state / data patterns
• Deliver fast and clear data visualizations for millions of data points from various sources
  
  

Backend Infrastructure

• Building features in Python (FastAPI) with PostgreSQL as our primary database.
• Managing AWS infrastructure — primarily ECS/Fargate, Lambda, S3, and related services.
• Designing APIs for the frontend (TypeScript) and partner integrations.
• Working on AI (LLM-powered) features end-to-end
  
  

The ROLE

You are not just an employee – you are a builder of the company.

You’ll be at the core of shaping Relixir’s product, technology, and trajectory – from hands-on full-stack development, to collaborating on the big decisions that define our future.

• Strategic Impact – Work directly with the founders to influence technical and product direction, deciding how we scale our platform and what bets we make in AI search automation.
• End-to-End Ownership – Take ideas from rough concepts to production-ready systems – UI/UX, frontend components, APIs, LLM usage, and everything in between. You’ll own critical features and ensure they’re fast, reliable, and a joy to use.
• Customer-Driven Development – Talk to customers, dig into their needs, and turn feedback into technical solutions that directly impact their growth.
  
  

About You

• Deeply Curious — You actively seek to understand complex systems, customer problems, and the latest technical possibilities. Curiosity drives your best work.
• Relentlessly Driven — You thrive in early-stage chaos. You move quickly, test bold ideas, and turn uncertainty into working solutions.
• True Owner — You don’t just “complete tickets.” You take full responsibility for delivering outcomes — finding a path forward even with incomplete information.
• Collaborative & Humble — You share ideas openly, listen actively, and care more about the best solution than being right. You’re confident in your skills but always learning.
  
  

Must-Haves

• In-person SF
• High-agency
• 1-3 years of experience building frontend & backend software for VC-backed startups
• Leveraged LLMs for building critical product features
• Strong proficiency in Next.js, Typescript, and Python
• Have completed at least one 0 -> 1 journey of a functional product
  
  

Nice-to-haves

• Entrepreneurial Mindset: Ex-founder or future founder
• AWS Infrastructure Management
• Timescaledb or any OLAP experience
• Qdrant/RAG, LangChain/LLM tooling, prompt/eval experience.
  
  

Why This Role is Special

• You’ll be part of the founding team — shaping the product, culture, and technical foundation of a YC-backed startup already working with 50 enterprise customers.
• You’ll have ownership — own UI/UX quality, API/DB design, and performance end-to-end. Shipping features that surface insights and actions from millions of AI-search data points each week.