Senior Full-stack Engineer

Who are we?Papaya Stars is the latest innovation from Papaya, a groundbreaking subsidiary launched to redefine the intersection of social platforms and gaming. Imagine Instagram, Roblox, and TikTok Challenges rolled into one – that’s the revolution we’re building.Our mission? Empower creators and players with advanced tools and an immersive platform that’s fun, engaging, and cutting-edge.The role:We’re looking for a Senior Full-Stack Engineer who thrives in fast-paced, experimental environments. You’ll be the kind of builder who loves turning ideas into end-to-end features - from concept to deployment - combining React Native on the client side with a .NET-based backend.This role is backend-oriented but requires strong full-stack ownership, helping us design, develop, and launch monetization-focused and experimental features that drive engagement and growth.Responsibilities: Design, build, and maintain scalable mobile features using React Native and .NET Core.Take features end-to-end - from ideation and prototyping to production rollout and performance optimization.Collaborate closely with Product, Design, and Data teams to experiment rapidly, test hypotheses, and improve market fit.Implement and iterate on monetization-related functionalities, in-app experiences, and growth-driven mechanics.Debug complex technical issues across the stack and improve performance and reliability.Contribute to architecture decisions, code reviews, and mentoring as the team grows.Requirements: 4+ years of experience in software development, with hands-on full-stack experience (React or React Native + .NET Core).Proven experience building consumer-facing features (B2C, gaming, e-commerce, or social platforms preferred).Strong understanding of API design, backend architecture, and cloud environments.Practical experience with mobile development (React Native or native mobile).Comfort with rapid prototyping, working iteratively, and adapting to changing priorities.Ability to handle both feature implementation and DevOps/infrastructure tasks when needed.Excellent problem-solving, debugging, and communication skills.Nice to have:Experience with machine learning algorithms or recommendation systems.Experience with GraphQL.Familiarity with feature flagging, experimentation frameworks, or A/B testing.What we offer:Join a profitable company with the heart of a startup – stable, growing, and full of energy.Enjoy a hybrid work model with flexibility and a growing Warsaw office.Receive competitive compensation tailored to the Polish market - B2B Service agreementComfortable office in central Warsaw equipped with all the necessary tools to conquer the universeLuxmed Medical servicesMonthly 'Pyszne.pl' voucherMultisport cardMonthly Happy HoursSnacks and Breakfasts