Desarrollador/a Fullstack (con foco en IA) — Madrid | Híbrido

Fullstack Developer (AI-Focused) — Madrid | Hybrid

At Tendios, we build AI-powered solutions that help our clients move faster and smarter. We're growing — and we're looking for a Fullstack Developer to join us in Madrid and work hand-in-hand with one of our key clients in the city.

The role

You'll split your time between Tendios and a client engagement in Madrid (2–4 days per week on-site with the client, the rest hybrid with our team). You won't just be writing code — you'll be the bridge between our product expertise and the client's day-to-day needs, helping them get the most out of our platform and AI tooling.

What you'll do

• Build and ship features across our stack — heavier on the backend, with some frontend work when needed

• Design and evolve APIs, services, and data models that power AI-driven workflows

• Work directly with a client in Madrid: understanding their problems, proposing solutions, and delivering them

• Integrate and experiment with modern AI tools (LLM APIs, agentic workflows, RAG, etc.) to push what our product can do

• Collaborate with our team remotely on architecture, code reviews, and product direction

What we're looking for

• Solid experience with Node.js / TypeScript on the backend

• Comfortable with Vue on the frontend (you don't need to be a CSS wizard, but you should be able to ship a clean UI)

• Working knowledge of both SQL and NoSQL databases — you understand when to use which and why

• Hands-on experience with AI tools and LLM APIs (Claude, OpenAI, or similar) — prompt engineering, function calling, and basic agentic patterns

• A pragmatic mindset: you ship, you iterate, you talk to users

• Based in Madrid (or willing to relocate) and comfortable working on-site with a client part of the week

• Fluent in English; Spanish is a strong plus given the client context

Nice to have

• Experience consulting or working embedded with a client team

• Familiarity with cloud infrastructure (AWS, GCP, or similar)

• Interest in AI product development beyond just calling APIs — you've built something with agents, RAG, or evals

What we offer

• A hybrid setup based in Madrid

• A varied role that mixes product work at Tendios with real client impact

• Direct exposure to cutting-edge AI tooling — we're not just talking about it, we're building with it

• A small, ambitious team where your work is visible and your ideas matter

Interested? Send us a quick note and your CV — we read every application.

A few notes on choices I made:

• No seniority label as you requested, but the phrasing ("solid experience," "hands-on," "working knowledge") naturally filters for junior-to-mid without scaring off the right people or attracting overpaid seniors.

• No salary listed — common on LinkedIn for this band, and it gives you negotiation room. If you want to include it (LinkedIn does boost visibility for posts with salary), I'd suggest "€30,000–€35,000 + benefits" or just "Competitive."

• Spanish framed as "strong plus" rather than required — broadens the pool slightly while signaling it matters for the client work.

• I leaned into the consulting/client angle since that's the differentiator: it makes the role sound more interesting than a typical dev seat, which helps justify the salary band.