Senior Backend Engineer

Upside

6d • $20,800 - $25,900 • Hybrid

About The Position

Upside is a software consultancy built by engineers, for engineers. We partner with global companies to solve real, complex technical challenges. We’re deep into Applied AI and R&D, building both production-grade platforms for clients and our own open-source tools like Enthusiast (Agentic AI framework). We operate in a Forward-Deployed model. We don’t sit behind a wall of specs or wait for the tickets. We get into the trenches with the client, identify the actual challenges, and take full ownership of the solution. Our teams are small (3–9 people), autonomous, and cross-functional. What it means for you You'll work with a capable and driven team, and partner directly with senior business leaders on technical decisions, shaping systems - not just implementing them. You’ll have the autonomy to choose the right tools and the ownership to ensure the architecture performs under pressure.Your focus stays where it counts: mission-critical logic and high-impact experiments, not repetitive tasks and countless meetings. You’ll contribute to strategic open-source projects and build AI-driven solutions. Role Overview As a Senior Backend Engineer, you’ll be the backbone of our development efforts and a key driver of our engineering culture. You will design, build, and scale resilient systems for international clients while staying close to the code. We’re looking for someone who brings ready solutions rather than problems to solve, and treats the client’s product as their own. This isn't a short-term opportunity - we’re looking for a partner to grow with us, someone who thrives in a highly collaborative environment and proactively shares "lessons learned" to level up the entire team.

Requirements

• 5+ years of building web applications (preferably in Python frameworks).
• Completed university degree in computer science, data science or similar field
• Deep understanding of monoliths, microservices, and messaging patterns.
• Expert knowledge of PostgreSQL and performance optimization at scale.
• Practical experience with CI/CD, Docker, and AWS/GCP.
• Proactive, technology-driven, and ready to experiment.
• You use tools like Claude or Cursor to move faster.
• Fluent (C1) English for direct client collaboration.

Nice To Haves

• Python, PostgreSQL, AWS, Docker, Kubernetes.
• Ruby is present in some of our projects but we are Python first.

Responsibilities

• Drive technical direction: Own the architecture and implementation of complex backend systems.
• Problem Solving: Identify systemic risks before they manifest and propose clear, actionable ways to bypass them.
• Consulting: Work directly with stakeholders to translate business needs into scalable technology.
• Mentorship: Share your observations and "lessons learned" to help the whole team level up.
• AI Integration: Identify where Applied AI can actually improve a product and lead the implementation.

Benefits

• Transparent progression path. We have defined engineering levels with clear criteria - you'll know exactly what each role looks like, and what it takes to get from one to the other. No ambiguity, no waiting for someone above you to move on.
• Compensation & Location
• On-site in Kraków; Hybrid; remote from anywhere in Poland with regular team on-sites.
• Salary: Senior Engineer: 20 800 - 25 900 PLN net + VAT
• Lead Engineer: >26 500 PLN net + VAT

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: Associate degree