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

📌 Senior/Principal Engineer - Software (m/f/d) (Valencia)
🏢 SKLUM
📍 Valencia