Staff Software Engineer - Backend

ABOUT US Our vision is a world where every patient feels cared for and every doctor has the capacity to care. Our mission is to end the second shift. For most doctors in Latin America, the workday doesn't end when the last patient leaves. A second shift starts on WhatsApp: patient messages, rescheduling, follow-ups and payments, often late into the night. Leona takes that shift off their hands. Our AI assistant reads and answers patient WhatsApp threads, books appointments, and is expanding into billing and payments for medical practices. Today, doctors across 28 specialties in 14 countries use Leona to manage relationships with their patients. We're building toward a future where patients feel cared for between visits, not just during them, and where doctors get their evenings back, while increasing their earnings. With bases in San Francisco and Mexico City, our team brings together years of experience scaling companies like Uber, Rappi, and Modern Fertility across the US and Latin America. We're backed by a16z, General Catalyst and Accel, along with a remarkable group of angels including the founders of Nubank, Rappi, and Maven Clinic. TECH CHALLENGE We’re looking for an experienced software engineer to help us shape and scale Leona. Leona is reimagining how the world interacts with care — starting with doctor-patient communication on WhatsApp. We are building an an AI-powered platform that automates clinical workflows to empower doctors to save time, reduce burnout, and deliver better, more personalized care at scale. Patients today expect round-the-clock access to personalized care, but doctors are stuck with outdated, fragmented tools; Leona bridges that gap with intelligent automation and seamless messaging. If you’re driven by tough engineering and user experience challenges, love wearing many hats, and thrive in taking products from 0 to 1, this role is for you. RESPONSIBILITIES - Take full ownership of projects that are both technically complex and business-critical - Collaborate closely with design, operations, data science, and medical professionals to deliver impactful product experiences - Work side-by-side with our CTO to evolve our engineering strategy and improve how we build - Help shape technical direction and product decisions as a core member of a small, high-performing team REQUIREMENTS - 6+ years of relevant experience, with a strong track record of building and scaling complex software systems (startup experience is a plus!) - Deep expertise in backend development using modern technologies (we use Python on the backend; clients are built in Flutter), and familiarity with managing production-scale infrastructure within AWS - Comfortable working across the stack and owning projects end-to-end — from idea to launch to scale - Strong understanding of modern AI technologies — you stay current with the tooling landscape and confidently apply AI/ML to real-world problems - Excellent communication and collaboration skills - A builder’s mindset and love for creating things that make a difference We’d love to work with someone who: - Thrives in ambiguity and fast-moving environments - Loves collaborating with talented cross-functional teammates - Is energized by the challenges and opportunities of early-stage startups - Is mission-driven and passionate about improving health outcomes - Is curious, resourceful, and always looking to innovate Bonus points for: - Experience in health tech or building communication tools (messaging, collaboration, etc.) - Spanish fluency