Principal Engineer-Client Platform

Klarna; Stockholms kommun; On-site; SEK 600,000 - 900,000; Full time

Job summary

Klarna is seeking an experienced engineer for its client platform focused on React Native. The candidate will own critical components, lead large initiatives in JavaScript and TypeScript, and mentor other engineers to uphold high-quality standards. You'll work on complex technical challenges that impact the entire platform's scalability and maintainability. A strong foundation in AWS, CI/CD, and a hands-on approach is essential for success in this role located in Stockholms län.

Qualifications

• Expertise in React Native and frontend platform.
• Proficiency in JavaScript and TypeScript.
• Experience with frontend build systems like Babel and Webpack.
• Solid understanding of AWS fundamentals.

Responsibilities

• Own and evolve core parts of the Klarna client platform.
• Solve complex technical problems impacting the platform.
• Lead initiatives involving JavaScript, TypeScript, and native integrations.
• Mentor engineers and conduct code architecture reviews.

Skills

React Native

JavaScript

TypeScript

Frontend tooling

AWS fundamentals

CI/CD pipelines

Node.js

Database fundamentals

Security and privacy fundamentals

Job description

Core responsibilities

• Own and evolve core parts of the Klarna client platform with a strong React Native focus, shaping foundational capabilities used across the app ecosystem.
• Solve complex, cross-cutting technical problems that impact developer experience, stability, scalability, and long-term maintainability of the platform.
• Balance short-term delivery needs with long-term platform strategy, ensuring solutions are sustainable and aligned with the broader evolution of the Klarna app.
• Act as a technical multiplier by providing mentorship, conducting thoughtful code and architectural reviews, and guiding engineers toward high-quality platform standards.

What you will do

• Own and evolve core parts of the Klarna client platform with a strong React Native focus, shaping foundational capabilities used across the app ecosystem.
• Solve complex, cross-cutting technical problems that impact developer experience, stability, scalability, and long-term maintainability of the platform.
• Lead large initiatives spanning JavaScript and TypeScript, frontend build tooling, native iOS and Android integrations, and CI/CD pipelines.
• Balance short-term delivery needs with long-term platform strategy, ensuring solutions are sustainable and aligned with the broader evolution of the Klarna app.
• Act as a technical multiplier by providing mentorship, conducting thoughtful code and architectural reviews, and guiding engineers toward high-quality platform standards.

Who you are

• A React Native and frontend platform expert with strong platform thinking and a hands‑on mentality.
• Deeply knowledgeable about React Native internals, including how it builds, runs, and integrates with iOS and Android.
• Highly proficient in JavaScript and TypeScript, with a strong understanding of runtime behavior and architecture patterns.
• Experienced with frontend build systems and tooling, including bundlers, transpilers, Babel, Metro, and Webpack concepts.
• Comfortable debugging complex runtime and build-time issues across the JavaScript to native boundary.
• Proven in evolving React Native at scale, including managing upgrades, shaping architecture, and improving tooling.
• Solid in basic AWS fundamentals such as compute, IAM, networking, monitoring, and database basics.
• Familiar with CI/CD pipelines and modern delivery practices.
• Knowledgeable in security and privacy fundamentals.
• Comfortable working with Node.js, Express, and database fundamentals.

Awesome to have

• Principal-level problem-solving capability without requiring deep native-specialist expertise.
• Comfortable owning ambiguous, high-impact problems and driving them to resolution.
• Thinks in platforms rather than features, with a systems-oriented mindset.
• Pragmatic and delivery-focused, while remaining opinionated about long-term quality and architectural integrity.
• Actively mentors others, raises the technical bar across teams, and contributes as a collaborative, high-trust team player.