Senior Fullstack Engineer

Upside Lab sp. z o.o.; Kraków; Hybrid; PLN 240,000 - 320,000; Full time

Job summary

A dynamic technology company is seeking a Senior Fullstack Engineer to design and develop robust backend systems for client-facing platforms. The ideal candidate will have over 5 years of experience in building web-based applications and proficiency in backend and frontend technologies. This role offers flexible working from Kraków or fully remote in Poland, alongside a supportive and collaborative culture.

Benefits

Transparent progression path

Flexible work options

Additional paid days off

Collaborative company culture

Support for ongoing learning

Qualifications

• 5+ years of commercial experience in building web-based applications.
• Experience with at least one language from the backend stack (Ruby, Python, JavaScript) or willingness to learn.
• Experience with at least one frontend stack (Vue, React) or willingness to learn.
• Great command of written and spoken English.

Responsibilities

• Lead the design and development of backend systems for client-facing platforms.
• Contribute to refining engineering methodologies and practices.
• Work collaboratively within a development team.
• Engage with business stakeholders to design technology solutions.
• Evaluate and incorporate new technologies to improve backend systems.

Skills

Building web-based applications

Ruby

Python

JavaScript

Vue

React

SQL and relational databases

Continuous Integration

Stakeholder communication

Software development cycle

Job description

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 Senior Fullstack Engineer, you will play a pivotal role in designing, developing, and maintaining production-grade platforms for our global clients. This position is at the heart of our development efforts, contributing significantly to the backbone of our client-facing solutions. You'll be part of a dynamic development team, sized between 3 to 9 members, dedicated to crafting scalable and resilient backend systems.

Requirements include:

• Extensive commercial experience in building web-based application (+5 years).
• Experience in at least one of Upside’s backend technology stack: Ruby, Python, JavaScript or the willingness to learn based on your current skills.
• Experience in at least one of Upside’s frontend technology stack: Vue and React or the willingness to learn based on your current skills.
• In-depth understanding of SQL and relational databases.
• Experience with Continuous Integration and Continuous Delivery.
• Experience in direct work with different stakeholders (e.g. Product Owners or Business Founders) in a consulting setting.
• Deep understanding of end-to-end software development cycle.
• Great command of written and spoken English.

Key Responsibilities:

• Design and Development: Lead the design and development of robust backend systems that serve as the backbone for our client-facing platforms. Ensure these systems are scalable, maintainable, and capable of handling the needs of global clients.

• Engineering Best Practices: Actively contribute to refining our engineering methodologies and practices. Advocate for code quality, security, and efficiency.

• Team Collaboration: Work closely within a development team, fostering a collaborative environment where ideas and best practices are shared and implemented.

• Stakeholder Communication: Engage directly with business stakeholders, consulting on and designing technology solutions that meet their needs. Your role will involve translating complex technical concepts into business-friendly language.

• Continuous Improvement: Constantly evaluate and incorporate new technologies or methodologies to improve the efficiency and reliability of our backend systems.

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.

Salary:

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

Location:

Office in Kraków, hybrid, fully-remote.