Senior Fullstack Engineer - End-to-End AI Impact

upside; Polska; Hybrid; PLN 232,000 - 289,000; Full time

Job summary

Upside is seeking a Senior Fullstack Engineer to design and scale resilient systems from the ground up, bridging backend logic and frontend experience for a production-grade product.

You will own the entire product experience, collaborating with stakeholders to understand what’s possible with modern tech and AI. You’ll drive solutions across the stack with autonomy and accountability.

Qualifications

• 5+ years of building complex web applications.
• Backend: Strong proficiency in Python or Ruby.
• Frontend: Mastery of Vue.js or React.js.
• Infrastructure: Solid understanding of SQL (PostgreSQL), CI/CD, and cloud environments.
• AI-Native: You use tools like Claude or Cursor to build better and faster.
• English: Fluent (C1) for direct client collaboration.

Responsibilities

• End-to-End Ownership: Lead the design and implementation of both backend systems and frontend interfaces.
• Proactive Solutions: Don't just flag blockers—come with proposals and experiments to bypass them.
• Consulting: Translate complex business needs into elegant, scalable fullstack architecture.
• Engineering Standards: Advocate for code quality, security, and performance across the entire repo.
• Continuous Improvement: Constantly evaluate new tech (especially AI/LLM) to improve delivery.

Skills

Backend development (Python/Ruby)

Frontend frameworks (Vue/React)

SQL & CI/CD

Cloud environments

AI tools (Claude/Cursor)

English (C1)

Tools

PostgreSQL

AWS

Docker

CI/CD

Job description

Upside is seeking a Senior Fullstack Engineer to design and scale resilient systems from the ground up, bridging backend logic and frontend experience for a production-grade product.

You will own the entire product experience, collaborating with stakeholders to understand what’s possible with modern tech and AI. You’ll drive solutions across the stack with autonomy and accountability.