CareerOS is a B2B2C career platform serving 100+ top MBA programs worldwide - including Oxford, INSEAD, London Business School, Georgetown, and Notre Dame - along with 30+ employers. We help 500K+ users land jobs they love. We're a small, high-output team based in Barcelona, operating with American startup intensity - we ship fast, own our decisions, and push each other to do great work.

We work in small squads, each owning their own area of the product end-to-end.

We're looking for an Engineer who can work confidently across the full stack - React/TypeScript on the frontend, Node.js on the backend. You'll ship features end-to-end, make product decisions, and grow into a senior role with us.

What you'll actually do

You won't specialize in one corner. You'll build across the stack.

- Ship features end-to-end - From database to UI. You'll work across React/TypeScript and Node.js (with some legacy Go), owning features from start to finish.

- Make product decisions - See a confusing UX? Fix it. Have a better idea for an API design? Propose it and build it. We trust engineers to make smart calls on small-to-medium product decisions.

- Build with AI tools - We use AI coding tools daily (Claude Code, Cursor - team members pick what works for them). You should be comfortable (or excited) to work this way.

- Work directly with design - Implement pixel-perfect, responsive interfaces from Figma. Push back when something doesn't make sense.

- Own your code in production - We do continuous deployment. What you merge today is live today. You'll debug, monitor, and improve what you build.

What we're looking for

Must-haves:

- 3-5 years building production web applications, comfortable on both frontend and backend

- Strong React and TypeScript skills - You can build complex UIs confidently

- Backend experience with Node.js - You can write APIs, work with databases, and debug across the stack





- Solid SQL skills - You can write queries, understand schemas, and think about data

- Strong product intuition - You've shipped features where you made design and technical calls, not just followed tickets

- Excellent communication - You can articulate tradeoffs clearly, push back respectfully, and work well async

- Comfortable with ambiguity - Requirements will be fuzzy. You ask the right questions, make reasonable assumptions, and move forward without hand-holding

- Fluent English - We're a distributed team; clear written and verbal communication is essential

Strong signals:

- You've worked at an early-stage startup before (and liked it)

- You have side projects or open source contributions that show you build things because you're curious

- You've used AI coding tools and have opinions about them

- You care about craft - clean code, good abstractions, thoughtful UI details

What this role is NOT

Let's be honest about fit:
- ❌ Not a laid-back 9-to-5 - Startup doesn't mean less oversight and more flexibility. It means more ownership, higher stakes, and sometimes intense pushes. We respect personal time, but when we ship, we ship hard.

- ❌ Not highly structured - If you need detailed specs and clear roadmaps to function, this isn't the place.

- ❌ Not single-track - If you only want to do frontend or only backend, check out our other roles. This one requires range.

What you get

- Competitive salary + stock options (we'll discuss based on experience and location)

- Remote-friendly, with optional in-person time in Barcelona

- Small team where your work visibly matters - we have 500K+ users and real revenue

- Direct access to founders and fast decision-making

- Clear path to senior engineer as we scale from 5 to 10+ engineers

Don't check every box but think you'd be great? Apply anyway. We care more about trajectory and taste than credentials.

📌 Full Stack Engineer (Barcelona)
🏢 Careeros
📍 Barcelona