Senior Frontend Engineer (React/Vue)

At Upside, we’re not just shipping features - we’re partnering with ambitious companies across the globe to solve complex, meaningful problems through technology. We work in small, 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, an AI Agent framework tailored for e-commerce use cases.

Role Overview:

We are seeking a Senior Frontend Engineer to drive the design, development, and maintenance of high-quality platforms for global clients. In this role, you will be a key contributor to our client-facing solutions, ensuring performance, scalability, and reliability. You’ll collaborate within a dynamic team of 3 to 9 developers, working together to craft scalable and resilient systems.

• Extensive commercial experience in building web-based applications.

• In-depth knowledge of modern frontend stack and knowledge of at least one framework (React or Vue).

• Experience with Next.js or other SSR frameworks.

• Experience with GraphQL.

• Solid FP/OOP skills.

• 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.

Bonus Points if you have:

• Experience in advanced web animations (e.g. framer-motion, GSAP, Rive/Lottie).

• Experience in advanced web technologies such as WebGL, WebSockets, WebAssembly, web workers, and PWA.

Your responsibilities would be

• Developing complex digital platforms - from architecture decisions to implementation.

• Work in autonomous teams (3-9 people) delivering mission-critical systems.

• Collaborate directly with technology leaders, founders, and domain experts to shape solutions that drive real business outcomes.

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 careers@upsidelab.io

Salary:

Senior Engineer: 20 800 - 25 900 PLN net + VAT
Lead Engineer: >26 500 PLN net + VAT

Including additional days off

Location:

Office in Kraków, hybrid, fully-remote.