Senior Fullstack Engineer

Upside

2d • Hybrid

About The Position

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.

What it means for you
You’ll have a "Founder" mindset. You won’t just build a UI or a database - you’ll own the entire product experience. You’ll be a technical partner to stakeholders, helping them understand what’s possible with modern tech and AI. You’ll have the autonomy to experiment across the stack and the responsibility to deliver tools that actually solve business problems. You’ll work at the intersection of product thinking and engineering, deploying AI-augmented features across the entire stack.

Role Overview
As a Senior Fullstack Engineer, you’ll design and scale resilient systems from the ground up. You’ll bridge the gap between backend logic and frontend experience, ensuring a seamless, production-grade product.

Requirements

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

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.

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

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed