Senior Principal Software Engineer

THE ROLE & THE TEAM 

As a Senior Principal Engineer - React Native in the Client Foundations team, you will support our technical vision and strategy for the architecture that powers our Android, iOS and Web applications for 50M+ active customers. This team is the backbone of our customers’ experience, responsible for developing and maintaining best-in-class, high-performing platform infrastructure for Android and iOS, including our underlying Rendering Engine framework. We empower developers with robust tooling, ensure smooth production operations, and establish the testing best practices that keep the Zalando Fashion Store running at scale.

This is a pivotal role in Zalando’s strategic migration to React Native. You will jump into the most complex engineering challenges to ensure our transition is scalable, secure, and built for the future. We are looking for an experienced Principal Engineer with deep architectural fluency in the new React Native architecture and a proven ability to debug the entire stack, from React component re-renders down to specific C++ bindings or native module layers.

Beyond the code, you will spearhead a culture of performance optimization and operational excellence. You will partner with product leaders and engineering teams to deliver foundational capabilities, while ensuring our mobile apps remain fluid and responsive. As a technical mentor, you will guide experienced engineers through complex profiling techniques and set the standards for UI performance metrics, ensuring that our technology landscape remains a benchmark for the industry.

INCLUSIVE BY DESIGN

At Zalando, our vision is to be inclusive by design. And this vision starts with ourhiring - we do not discriminate on the basis of gender identity, sexual orientation, personal expression, ethnicity, religious belief, or disability status. You are welcome to leave out your picture, age, or marital status from your application. We only assess candidates on their qualifications and merit. 

We want to provide you with a great candidate experience. Feel free to inform us of any accommodations you may need, so we can best support you throughout the hiring process. 

do.BETTER - our diversity & inclusion strategy:https://corporate.zalando.com/en/our-impact/dobetter-our-diversity-and-inclusion-strategy

WHAT WE’D LOVE YOU TO DO (AND LOVE DOING) 

• Solve the Most Complex Engineering Challenges in Zalando’s React Native Migration: Play a pivotal role in our strategic journey to React Native (read more about our vision in our blog post: Accelerating Mobile App Development at Zalando with Rendering Engine and React Native). Leverage deep expertise in the new React Native architecture to resolve complex engineering challenges in massive-scale applications. Diagnose critical bottlenecks across the entire stack, from React re-renders to C++ JSI or native modules. Utilize expert proficiency with Xcode Instruments and Android Studio Profilers to fix blocked JavaScript threads, main thread bottlenecks, and native memory leaks.

• Champion a Performance-First Culture: Establish and lead a culture of performance optimization within the engineering organization. You will be responsible for setting performance budgets, integrating monitoring into CI/CD pipelines, and spearheading internal training to ensure we detect degradations before they reach production.

• Deliver Best-in-Class UI Experiences: Architect core app features and animations with performance as a primary consideration, applying your knowledge of when to utilize tools like react-native-reanimated for UI thread animations. You will use advanced profiling tools to analyze allocation timelines and optimize feature-rich interfaces, ensuring a fluid experience for our customers.

• Elevate Engineering Excellence and Mentorship: Act as a technical beacon for the mobile domain, mentoring experienced engineers on complex performance, profiling, and debugging techniques. You will communicate complex architectural decisions and trade-offs to stakeholders, ensuring technical alignment across the organization.

WE’D LOVE TO MEET YOU IF…

•  You have extensive experience developing large-scale React Native applications, with deep architectural fluency in the new React Native architecture, including Fabric, TurboModules, and JSI.

• You possess "full-stack" profiling capabilities, with the proven ability to debug the entire stack from a React component re-render down to specific C++ JSI bindings or native modules in Swift/Objective-C and Kotlin/Java.

• Your technical toolkit includes expert-level proficiency with native tooling, specifically Xcode Instruments and Android Studio Profilers, to identify main thread bottlenecks and memory leaks.

• You are proficient in advanced JS profiling using React Native DevTools and the Memory tab to analyze allocation timelines and detect JavaScript-based memory leaks.

• You approach engineering with a performance-first design mindset, knowing precisely when to use tools like react-native-reanimated and how to optimize feature-rich user interfaces.

• You have a history of establishing a culture of performance optimization, including setting performance budgets, integrating monitoring into CI/CD, and spearheading internal training programs.

• You are a strategic communicator and mentor, able to guide experienced engineers on complex debugging techniques and clearly explain architectural trade-offs to both technical and non-technical stakeholders. 

Zalando provides a range of benefits, here's an overview of what you can expect. Ask your Talent Acquisition Partner to learn more about what we offer.

• Employee shares program

• 40% off fashion and beauty products sold and shipped by Zalando, 30% off Lounge by Zalando, discounts from external partners

• 2 paid volunteering days per year

• Hybrid working model with up to 60% remote per week, actual practice is up to each team to best support their collaboration

• Work from abroad for up to 30 working days a year

• 27 days of vacation a year to start for full-time employees

• Relocation assistance available (subject to prior agreement)

• Family services, including counseling and support

• Health and wellbeing options (including Wellhub, formerly Gympass)

• Mental health support and coaching available

• Drive your development through our training platform and biannual peer-to-peer review