Senior Backend Developer

Simple Life App / Zing Coach

Remote, Europe, PLRemote

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Zing Coach is the world’s first AI Fitness Personal Trainer, revolutionising the way people approach health and wellness. Four years ago, we set out to replace traditional PT sessions with smart, personalised, motivating guidance powered by AI. We’re not just another app – we’re a movement, on a mission to help everyone reach their full physical and mental potential.We are looking for a Senior Backend Engineer to build and evolve backend services that power the Zing Coach product. This is a hands-on individual contributor role focused on shipping high-quality backend code, improving existing systems and approaches, and taking responsibility for production behaviour.<h3>Responsibilities</h3><ul class="ak-ul"><li>Backend feature development<ul class="ak-ul"><li>Design and implement backend features supporting core product experiences</li><li>Take work from ideation through deployment and production support</li><li>Design backend-first architecture used by mobile clients and internal services</li></ul></li><li>AI-backed product functionality<ul class="ak-ul"><li>Integrate backend with LLM-powered and ML-based systems</li><li>Handle latency, failure modes, and operational concerns around AI dependencies</li></ul></li><li>System improvement and scaling<ul class="ak-ul"><li>Improve performance, scalability and reliability of existing backend services</li><li>Work with relational databases: schemas, queries, migrations, and performance issues</li><li>Collaborate closely with mobile, ML, and product managers to deliver features end-to-end</li></ul></li></ul><h3>What we expect that you have</h3>Must-have<ul class="ak-ul"><li>Strong backend engineering experience with Python (Django and/or FastAPI)</li><li>Experience building and operating high-load backend systems</li><li>Experience with asynchronous systems</li><li>Good understanding of API design for backend ↔ client communication</li><li>Solid experience with relational databases (PostgreSQL preferred)</li><li>Strong execution and ownership mindset</li><li>Fluent English</li></ul>Nice to have<ul class="ak-ul"><li>Experience working with cloud infrastructure (AWS or equivalent)</li><li>Experience working on AI- or ML-enabled products</li><li>Experience with other languages (e.g. Go, Ruby)</li><li>Interest in health, fitness, or consumer-facing products</li><li>Fluent English</li></ul><h3>Why working at Zing is awesome</h3><ul class="ak-ul"><li>Be part of the fastest-growing fitness and lifestyle startup</li><li>AI and LLMs are core to the product and part of how we build software day to day</li><li>Backend systems with real scale, real users, and real constraints</li><li>AI-driven product where backend reliability and performance matter</li><li>Small team, high trust, and room to grow through responsibility</li></ul>Come be a part of something extraordinary at Zing AI Coach – where innovation meets inspiration, and every day brings new opportunities for growth and impact.If you are passionate about understanding user needs and contributing to the development of a user-centered product, we would love to hear from you. Join us and help us create an exceptional user experience for Zing Coach!

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