Senior Backend Engineer (Python/Ruby)

Upside is partnering with ambitious companies to solve complex problems through technology. We're a small, focused team that combines engineering, product thinking, and design to deliver outcomes. We work on open-source projects and build production-grade platforms for global clients.

Requirements

• Extensive commercial experience in building web-based applications (+5 years)
• Strong proficiency in at least one of Upside's core technology stack: Ruby, Python, JavaScript or the willingness to learn based on your current skills
• Solid understanding of software architecture principles: monoliths, microservices, asynchronous systems, messaging patterns, and scalability
• Deep knowledge of relational databases (we mostly use PostgreSQL) and performance optimization
• Working understanding of frontend frameworks and tools (e.g. Vue.js, React.js)
• Practical experience with Continuous Integration/Continuous Deployment (CI/CD) practices and modern cloud environments
• Strong consulting mindset - balancing technical excellence with client needs and communicating effectively with both technical and non-technical stakeholders
• Fluent English, with clear written and verbal communication

Benefits

• Transparent progression path
• Flexible work: office in Kraków, hybrid or remote from anywhere in Poland, with company on-sites
• Additional paid days off beyond national holidays
• A deeply collaborative, engineering-led company culture
• Support for ongoing learning