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, and we're growing with real revenue (not just runway).
We're a small, high-output team of 5 engineers based in Barcelona, scaling to 10+. We work in small squads, each owning their area of the product end-to-end. We ship fast, own our decisions, and push each other to do great work.
The RoleWe're looking for a Senior Product Engineer - someone who builds full features from database to UI, with strength in backend systems.
You'll work directly with the CTO and CPO, not through layers of management. You'll be in the room when decisions get made and have real input on what we build and how.
We call this a "Product Engineer" role because you won't just implement tickets. You'll own features end-to-end, make product calls, and ship things that matter to real users.
Tech stack: Node.js (primary for new code), some legacy Go (~20%), React/TypeScript on frontend. Infrastructure on GCP with Terraform.
Typical split: ~60% backend/infra, ~40% frontend - varies by project.
What You'll Actually DoShip full features, end-to-end - From schema design to API to UI. You'll own the whole vertical, not just one layer.
Build and maintain infrastructure - GCP, Terraform, CI/CD pipelines. You'll keep the systems running and improve them over time.
Optimize databases - Write complex queries, tune performance, design schemas that scale.
Make product decisions - See a better way to solve a user problem? Propose it and build it. We trust engineers to make smart calls on technical and product decisions.
Build with AI tools - We use Claude Code, Cursor, and other AI tools daily. You should be comfortable (or excited) to work this way.
Own your code in production - Continuous deployment means what you merge today is live today. You'll debug, monitor, and improve what you build.
Must-haves:
5+ years building production systems, with strong backend experience (Node.js or Go)
Solid SQL skills - complex queries, performance tuning, schema design
Infrastructure experience - GCP or AWS, Terraform, CI/CD pipelines
Comfortable across the stack - backend-focused but can ship real frontend features in React/TypeScript, not just "fix a button"
Strong product intuition - you've shipped features where you made architectural and product calls
Excellent communication - clear writing, respectful pushback, documentation others actually read
Comfortable with ambiguity - you ask the right questions, make reasonable assumptions, and move forward
Fluent English - we're distributed; clear communication is essential
Strong signals:
You've worked at an early-stage startup before (and liked it)
Experience with auth systems - OAuth, SAML, SSO, Auth0
Side projects or open source 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, reliable systems
Let's be honest about fit:
❌ Not a chill 9-to-5 - Startup means more ownership, higher stakes, and hard pushes around launches. We respect personal time and recover after sprints, 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 backend-only - You'll spend real time in React. If you want pure backend/infra, this isn't the role.
❌ Not frontend-heavy - If you want to go deep on UI/UX, we have a Frontend Product Engineer role.
You'll join as one of 5 engineers, growing to 10+. As we scale, there's a clear path to tech lead or staff engineer for the right person. You'll help shape engineering culture, not just inherit it.
What You GetCompetitive salary + stock options - we'll discuss based on experience and location
Remote-friendly - Barcelona hybrid optional, remote within CET ±2 hours
Small team, visible impact - 500K+ users, real revenue, your work matters
Work directly with CTO and CPO - fast decisions, no layers, real influence
AI-native team - we are using Claude Code and Cursor in our day-to-day and open to trying new
Don't check every box but think you'd be great? Apply anyway. We care more about trajectory and taste than credentials.
Skills Required
- 5+ years building production systems with strong backend experience (Node.js or Go)
- Solid SQL skills including complex queries, performance tuning, and schema design
- Infrastructure experience with GCP or AWS, Terraform, and CI/CD pipelines
- Comfortable across the stack and able to ship frontend features in React and TypeScript
- Strong product intuition and experience making architectural and product trade-offs
- Excellent written and verbal communication; fluent English
- Comfortable with ambiguity and autonomous decision-making
- Experience at early-stage startups
- Experience with auth systems (OAuth, SAML, SSO, Auth0)
- Side projects or open-source contributions demonstrating curiosity
- Familiarity using AI coding tools (Claude Code, Cursor) in development
- Attention to craft: clean code, reliable systems, good abstractions
What We Do
CareerOS is an integrated career development and execution platform designed to transform how universities support student careers. It provides smart, scalable tools for students to manage their career journey, including networking, job applications, and interview preparation. The platform also offers universities data-driven insights into student engagement and helps employers connect with top talent, creating a more structured and transparent ecosystem for early-career recruitment.
