Staff Software Engineer - Backend

ABOUT US Leona is on a mission to empower everyone to take the best care of themselves, their patients, and their loved ones. We have an ambitious goal: to transform the way the world interacts with healthcare, because where you live shouldn't determine the quality of care you receive. For patients, managing your health should feel empowering, not intimidating. For doctors, we want to eliminate the administrative noise so you can focus on what matters most: delivering exceptional care. We're reimagining what it looks like for doctors to care for patients in an AI-first world — starting with a platform that streamlines doctor-patient communication via WhatsApp, acting as an AI clinical assistant that automates non-urgent tasks, surfaces what's urgent, and gives patients the convenience of reaching their care team 24/7. With bases in San Francisco and Mexico City, our team brings together years of experience scaling companies like Uber, Rappi, Modern Fertility, and Wonder across the US and Latin America. We're backed by a16z, General Catalyst, and Accel, and a remarkable group of angels including the founders of Nubank, Rappi, and Maven Clinic. If you're hungry to build 0-to-1, and roll up your sleeves to make magic, thrive in ambiguity, and care deeply about building a better future, this role might be the perfect fit for you. 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 Patients today expect round-the-clock access to personalized care, but doctors are stuck with outdated, fragmented tools; Leona bridges that gap with intelligent automation and seamless messaging.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