Product Engineer (Full-Stack)

Karumi (YC F25); Madrid; Hybrid; USD 100,000 - 130,000; Full time

Benefits offered by this job

Meaningful equity stake

Visa sponsorship available

End-to-end ownership of features

Job summary

A promising tech startup in New York is seeking a full-stack developer to join its product engineering team. In this role, you'll build features that enhance user interaction with the platform, handle both frontend and backend tasks, and work on AI-powered integrations. Ideal candidates will have strong proficiency in React and Python, as well as experience with cloud services. The company offers meaningful equity, a small team environment, and visa sponsorship for qualified candidates.

Qualifications

• Strong full-stack development experience (frontend + backend).
• Proficient in React and modern JavaScript/TypeScript.
• Python skills with FastAPI or similar frameworks.

Responsibilities

• Build full-stack features from UI components to backend services.
• Design and implement responsive, intuitive user interfaces with React.
• Develop high-performance APIs using FastAPI and async Python.
• Deploy and monitor features across our AWS infrastructure.

Skills

Full-stack development experience

Proficient in React

Modern JavaScript/TypeScript

Python (FastAPI)

Experience with PostgreSQL

Experience with Redis

Comfortable with AWS

Job description

The Opportunity: Join our product engineering team in the US to build features that directly impact how customers experience and adopt our platform. This role bridges technical execution and product thinking - you'll ship user-facing features while making architectural decisions across the entire stack. You'll work end-to-end: designing interfaces, building APIs, optimizing performance, and deploying to production. We move fast, iterate with users, and expect engineers to own problems from concept to launch. We sponsor visas for qualified candidates.

Responsibilities

• Build full-stack features from UI components to backend services
• Design and implement responsive, intuitive user interfaces with React
• Develop high-performance APIs using FastAPI and async Python
• Work with LLM integrations, prompt engineering, and AI-powered workflows
• Deploy and monitor features across our AWS infrastructure
• Gather user feedback and iterate rapidly on what you ship

Technical Requirements

• Strong full-stack development experience (frontend + backend)
• Proficient in React and modern JavaScript/TypeScript
• Python skills with FastAPI or similar frameworks
• Experience with PostgreSQL, Redis, and async patterns
• Comfortable with AWS/Azure/GCP, deployment pipelines, and infrastructure basics
• Product mindset - you care about user experience and customers, not just code

Nice to Have

• Experience building with LLMs and AI-powered features
• Browser automation or headless browser technologies
• Design sensibility and attention to UI/UX details
• Previous startup or 0-to-1 product experience

Why Karumi

• Meaningful equity stake in a backed, fast-growing company
• End-to-end ownership of features users interact with daily
• Direct impact on product direction and company trajectory
• Small team where shipping matters more than process
• Visa sponsorship available