Principal Fullstack Engineer

Sklum Digital & AI is an agentic-native team: a small, high-leverage group that heavily uses agentic AI workflows to build applications and scale our impact far beyond traditional team sizes. For this role in particular, agentic fluency is essential — you will be expected to use agentic tooling every day to multiply your own output, and to help shape how the team leverages these tools.
We are looking for a Principal Fullstack Engineer to be a major hands-on builder of the new Sklum app, which we are building from scratch. This is a mobile-first fullstack role: the primary focus is React Native for mobile, extended with the backend work needed to deliver features end-to-end.
This is a primarily hands-on individual contributor role — you will spend most of your time writing and shipping production code. You will report to the Principal Engineer – Architect and work closely alongside the Principal Software Engineer – Backend & Data and other senior engineers to deliver the app from zero to one.
Mobile-First Fullstack Engineering
Design, build, and ship features end-to-end across the Sklum app — from the React Native mobile experience to the backend services that power it.
Own the mobile experience layer: architecture, navigation, state management, performance, offline behavior, and production-grade patterns in React Native.
Extend into the backend when needed: build APIs, services, and data flows that support the mobile experience, in close collaboration with the Backend & Data engineer.
Contribute to the web experience (React / Next.js) where features span platforms, ensuring consistency of behavior and design system across mobile and web.
Quality, Performance, and Craft
Write production-grade, well-tested, observable code; own features end-to-end from design through deployment and on-call.
Drive performance, reliability, accessibility, and security of the mobile experience.
Establish and maintain engineering standards for the fullstack work you touch — code quality, testing, CI/CD,



observability.
Use agentic AI workflows as a core part of day-to-day engineering — from design and coding to testing, review, and operations — to scale your own output and the team's capacity.
Contribute to the team's agentic operating model: identify where agents can take on more work, where guardrails are needed, and how to keep quality and security high.
Partner closely with the Architect, the Backend & Data engineer, product, design, and other specialists to deliver end-to-end capabilities.
Provide technical mentorship and code review, raising the bar for mobile and fullstack engineering across the team.
8+ years of professional software engineering experience, with a strong record of shipping production systems in hands-on roles.
~ Deep, hands-on expertise with React Native — including architecture, performance optimization, native module integration, and production-grade patterns at scale.
~ Strong backend engineering skills — designing and building APIs, services, and data flows that support consumer-facing mobile apps.
~ Working expertise with React and Next.js for web, and the ability to contribute to the web experience when features span platforms.
~ Solid understanding of mobile delivery practices: app store release processes, over-the-air updates, mobile observability, crash reporting, and A/B testing.
~ Experience in e-commerce, marketplace, retail, or other consumer-facing digital platforms.
~ Familiarity with operational systems that surround a consumer app (ERP, CRM, PIM, CMS) and how they connect to the mobile and backend layer.
~ Experience with cloud-native architectures (AWS and/or GCP), containerization, and modern CI/CD practices.
~ coding agents, autonomous workflows) as a core part of building software, and a demonstrated ability to scale personal and team output through them.
~ fluency in English is required.
~ Working proficiency in Spanish or Chinese is a plus.

Private health insurance from Day 1
This role sits at the core of SKLUM's Digital and AI team, directly shaping how supply chain decisions are made.

📌 Senior Engineer/Engineering Manager (Valencia)
🏢 SKLUM
📍 Valencia