Fullstack

Senior Full Stack Developer (Node.js Focus) – Open‑Source AI Platform

About the Project

We are building a sophisticated, open‑source AI conversational platform that integrates multiple AI providers to deliver a rich, cutting‑edge user experience. We are looking for an experienced Senior Full Stack Developer to join our core team as a B2B partner.

Setup & Work Arrangement

Contract: 100% B2B / Independent Contractor (You must be registered as an Autónomo or have a corporate entity in Spain).

Location: Hybrid. We require availability to be on‑site at our Madrid office 2‑3 days per week for architectural alignment, team syncs, and workshops. The rest of the time is remote.

Language: Fluent English is required.

What You Will Do

Take ownership of the backend components, building a sophisticated AI chat platform.

Implement new AI provider integrations (OpenAI, Claude, etc.) an...