Our 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.If you're motivated by real technical challenges, modern architecture, and building AI-driven features from the ground up (not just buzzwords), keep reading.The RoleThe selected candidate will join an agile team with real autonomy.Core responsibilities include:Designing and building scalable backend systems (Python + Django REST Framework).Working on complex integrations across payments, ecommerce, logistics, and automation.Participating in architectural decisions and technical roadmap definition.Driving engineering quality through testing and TDD practices.Mentoring teammates and contributing to product direction.Helping build the AI infrastructure from scratch.What We're Looking ForTechnical Background5+ years of backend development experience (senior or lead level).Strong experience withPython and Django REST Framework (or similar: Ruby on Rails, Phoenix, Laravel, etc.).Strong testing mindset (ideally TDD).Knowledge of PostgreSQL, AWS, and security best practices.Comfortable with occasional frontend work (while remaining backend-focused).Solid understanding of system design and scalability.Product & BusinessGenuine curiosity about how users experience the product.Ability to translate design specs into actionable engineering tickets.Interest in understanding the why, not just the what.AIInterest in AI for productivity (code generation, automation).Excitement about building AI features and infrastructure from scratch.Curiosity about emerging AI capabilities.CommunicationFluent in English (spoken and written).Spanish is a plus.Pragmatic problem-solver who balances speed