Middle Full-Stack Engineer (Frontend-focused, React + Node/Go) Offline

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 a Middle Full-Stack Engineer with a strong frontend focus who can work confidently across the stack - React/TypeScript on the frontend, Node.js/Go on the backend. You'll primarily build user-facing product experiences, ship features end-to-end, contribute to product decisions, and grow into a senior role with us.
 

What you'll actually do

You won't specialize in just one corner. You'll build across the stack, with your center of gravity on the frontend.

• 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:

• 2–4 years building production web applications, comfortable across frontend and backend
• Strong React and TypeScript skills - You can build complex UIs confidently
• Backend experience with Node.js or Golang - 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 (based on experience and location).
• Remote-first setup with optional Spain-based employment.
• Small team where your work directly impacts 500K+ users.
• Direct access to founders and fast decision-making.
• Clear path toward Senior Engineer as we scale.