Lead Backend Developer

About Us We're building the next generation of smart calculators for modern retailers — tools that go far beyond basic math. These devices integrate dynamic QR code generation, digital payments, inventory tracking, and more. Think of it as a POS terminal disguised as a calculator — but way smarter. Our mission is simple yet ambitious: to replace over 30 million traditional calculators sitting on shop counters across the world. If you're passionate about creating intuitive, impactful hardware + software systems that empower everyday users — join us in redefining what a calculator can do.

About the Job We are looking for a hands-on

Backend Lead Engineer

to own, scale, and optimize the backend systems powering our next-generation smart calculator ecosystem. This role involves leading backend architecture, mentoring engineers, and building robust services that support payments, IoT device sync, inventory, and real-time retail workflows. The ideal candidate enjoys designing large-scale distributed systems, writing clean and reliable backend code, and working closely with cross-functional teams across firmware, app, and DevOps. This role is ideal for engineers who want deep ownership, architectural influence, and the opportunity to shape the technical foundation of a fast-growing product.

Key Responsibilities Backend Architecture & Development Design and develop scalable backend services using Java/Kotlin and Spring Boot. Build and maintain APIs for payments, inventory, device sync, and retail workflows. Optimize system performance, database queries, and API latency for real-world usage. Lead architectural decisions in collaboration with the CTO and Engineering Manager.

Technical Leadership & Mentorship Guide backend engineers on best practices, design patterns, and system design. Conduct code reviews, ensure code quality, and maintain engineering standards. Support team members in debugging complex backend issues and production incidents.

Cross-Functional Collaboration Work closely with the Mobile App team to define API contracts and data flows. Collaborate with Hardware & Firmware teams to design device communication protocols. Coordinate with DevOps on infrastructure, deployments, monitoring, and CI/CD.

System Reliability & Operations Own critical production systems, including incident response and root-cause analysis. Implement logging, monitoring, and observability practices across services. Ensure backend readiness for 10x scale and multi-region deployments.

Required Skills Strong proficiency in Java/Kotlin with deep experience in Spring Boot. Hands-on experience designing and scaling distributed backend systems. Solid understanding of PostgreSQL, DynamoDB, caching, and queueing systems. Experience working with AWS services such as EKS, EC2, RDS, S3, and Lambda. Familiarity with Docker, CI/CD pipelines, and cloud-native deployments. Strong grasp of system design fundamentals (scalability, reliability, fault tolerance). Ability to debug complex production issues in distributed environments. Strong communication and collaboration skills across technical and non-technical teams

Qualifications 7–10+ years of backend engineering experience, including team or project leadership. Demonstrated experience owning production systems at scale..

Optional / Nice-to-Have Skills Experience with Python and FastAPI for microservices. Background in FinTech or payment gateway integrations. Exposure to IoT or device synchronization systems. Experience scaling systems from early-stage to high-traffic production systems. Contributions to open-source or technical writing.