Staff Software Engineer

At Upside, we’re partnering with ambitious companies across the globe to solve complex, meaningful problems through technology. We work in focused teams, combining engineering, product thinking, and design, to deliver outcomes, not just output.

Open-source is a strategic part of our work. We build and maintain a number of open-source projects that support our clients and internal R&D. Our latest release is Enthusiast, a customizable agentic AI toolkit for e-commerce.

Role Overview :

As a Staff Software Engineer, you will guide engineering teams in delivering production-grade platforms and AI-driven solutions for global clients. You’ll shape technical direction, support team members, and collaborate closely with business leaders to design systems that truly move the needle. This is a hands-on role : while you’ll be deeply engaged in architectural decisions and strategic conversations, you’ll also remain close to the code, ensuring that technical excellence is a lived standard, not just an aspiration.

Requirements :

Extensive commercial experience in building web-based applications (+7 years), including 2+ years in a leadership role (Tech Lead, Team Lead, or similar).

Solid expertise in at least one of the following frameworks : Python, Ruby, JavaScript – and readiness to explore new technologies when needed.

Proven ability to design and oversee complex architectures (monoliths, microservices, distributed and asynchronous systems, messaging patterns, scalability).

Strong understanding of databases (PostgreSQL preferred) and performance optimization at scale.

Experience in cloud-native environments and CI / CD practices.

Excellent consulting skills – balancing technical excellence with business needs, and the ability to communicate effectively with both technical and non-technical stakeholders (CTOs, founders, product leaders).

Demonstrated ability to mentor engineers, provide constructive feedback, and foster technical growth.

Fluent English (clear written and verbal communication).

Key Responsibilities :

Leading, autonomous teams (3–9 people) in designing, building, and deploying complex digital platforms.

Driving architecture and technology choices for large-scale systems.

Mentoring engineers, fostering technical excellence, knowledge sharing, and a collaborative culture.

Partnering directly with clients, technology leaders, and founders to co-create impactful solutions.

Balancing technical depth with business context to deliver long-term value.

Ensuring engineering best practices, code quality, and CI / CD pipelines are consistently applied.

Staying close to AI / ML solutions and identifying opportunities to integrate them into client solutions.

What We Offer

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.

If you didn't find all the information you were looking for, have a look at our handbook - it covers a variety of different matters that could be important at this stage. If there's anything else we did not mention that you're interested in - share your thoughts with us