We are creating the freedom for SMEs to succeed by delivering Europe's leading finance workspace with banking at its core, augmented by financial tools. Our culture puts customer satisfaction at the core of what we do, as proven by our Net Promoter Score of 75 (more about our culture here). Founded in 2017 by Alexandre and Steve , Qonto has grown to 1,600+ Qontoers serving over 600,000+ customers across 8 European countries. With 80+ nationalities, 45% women, of which 56% of women in our leadership team, diversity isn't a program; It's who we are. We want people who experiment without waiting for permission, push AI beyond the obvious, know when to trust it, and when to question it. Join us as Principal Backend Engineer in the Foundations domain and help scale the critical systems that power Qonto's 600,000+ customers — before they become bottlenecks. You'll drive company-wide backend initiatives spanning transactions, search, monetization, permissions, and integrations.
Anticipate and solve scale challenges before they hit:



You'll map technical risks across Foundations' core systems — ~600k daily transactions approaching 1B total, search indexing, billing — and drive the architectural work that keeps Qonto's growth ahead of its infrastructure.
You'll own end-to-end programs spanning multiple teams, touching Legal, Risk, Compliance, and leadership, with real business consequences.
Multiply the engineering org around you: You'll raise the bar for groups of engineers through mentoring, coaching programs, and technical enablement — not just one-on-ones.
Bridge business goals and backend decisions: Large-scale backend architecture: You've designed and scaled high-volume systems — transactions, search/indexing, billing, or similar — under real growth pressure.
You've driven complex, multi-team initiatives that touched Legal, Risk, Compliance, and leadership, and you can tie every technical decision to a business outcome.
Usage and data volumes are growing fast — you'll a

📌 Principal Backend Engineer (Barcelona)
🏢 Qonto
📍 Barcelona