POur client, a fast-growing international startup, is redefining how people unlock the value of what they already own, turning circularity into a smart, frictionless payment experience. With a live product, real traction, and a modern tech stack, they are expanding their engineering team with a senior backend profile who enjoys building scalable, resilient systems that have a direct impact on business. /ppIf you’re motivated by real technical challenges, modern architecture, and building AI-driven features from the ground up (not just buzzwords), keep reading. /ppbr/ppbThe Role /b /ppThe selected candidate will join an agile team with real autonomy. Core responsibilities include: /pulliDesigning and building scalable backend systems (Python + Django REST Framework). /liliWorking on complex integrations across payments, ecommerce, logistics, and automation. /liliParticipating in architectural decisions and technical roadmap definition. /liliDriving engineering quality through testing and TDD practices. /liliMentoring teammates and contributing to product direction. /liliHelping build the AI infrastructure from scratch. /li /ulpbr/ppbWhat We’re Looking For /b /ppbTechnical Background /b /pulli5+ years of backend development experience (senior or lead level). /liliStrong experience with Python and Django REST Framework (or similar: Ruby on Rails, Phoenix, Laravel, etc.). /liliStrong testing mindset (ideally TDD). /liliKnowledge of PostgreSQL, AWS, and security best practices. /liliComfortable with occasional frontend work (while remaining backend-focused). /liliSolid understanding of system design and scalability. /li /ulpbr/ppbProduct Business /b /pulliGenuine curiosity about how users experience the product. /liliAbility to translate design specs into actionable engineering tickets. /liliInterest in understanding the why, not just the what. /li /ulpbr/ppbAI /b /pulliInterest in AI for productivity (code generation, automation). /liliExcitement about building AI features and infrastructure from scratch. /liliCuriosity about emerging AI capabilities. /li /ulpbr/ppbCommunication /b /pulliFluent in English (spoken and written). Spanish is a plus. /liliPragmatic problem-solver who balances speed and quality. /liliCollaborative mindset with mentoring experience. /li /ulpbr/ppbBonus /b /pulliExperience in fintech, payments, or ecommerce. /li /ulpbr/ppbTech Stack /b /pullibBackend: /b Python, Django REST Framework /lilibDatabase: /b PostgreSQL /lilibFrontend: /b Angular / Vanilla JS /lilibIntegrations: /b PHP (ecommerce plugins) /li /ulpbr/ppbWhat the Company Offers /b /pulliCompetitive compensation. /liliFully remote role (optional hub in Barcelona). /liliFlexibility: 5-hour overlap with Spanish business hours (9–19 CET). /liliHigh autonomy in both technical and product decisions. /liliOpportunity to build AI infrastructure from zero. /liliGrowing team with strong technical leadership. /li /ul