Lead JavaScript Engineer

We’re looking for an experienced Lead Software Engineer to join Klarna’s engineering team. You’ll play a critical role in building scalable, reliable systems and driving technical excellence across our products. This position combines hands-on coding with leadership, mentorship, and strategic decision-making.

We offer a hybrid work model in Warsaw’s vibrant Wola district. English fluency and eligibility to work in Poland are essential, as is the successful completion of a background check to meet the rigorous standards of the financial domain.

Main responsibilities:

1. System Architecture & Technical Leadership: Design and lead the development of scalable, high-performance systems that meet business goals.
2. Kafka Management: Handle advanced Kafka configurations, manage traffic, and optimize topic production and consumption.
3. Backend Engineering: Develop and test robust applications using Node.js, TypeScript, and Jest.
4. Database Design: Architect and maintain PostgreSQL and DynamoDB databases for performance and scalability.
5. Project Ownership: Drive delivery, manage stakeholders, identify and address technical debt, and define technical roadmaps.
6. Mentoring & Team Development: Guide engineers in their growth, conduct code reviews, lead demos, and create technical documentation.
7. Quality Assurance: Apply best practices in software testing, ensuring reliability and maintainability across codebases.
8. Cross-functional Collaboration: Align with product, design, and infrastructure teams to deliver integrated, high-impact features.

Requirements:

1. 10+ years of professional software engineering experience, including significant time in technical leadership roles.
2. Expertise in Kafka, including production-ready setup, optimization, and usage patterns.
3. Strong command of Node.js, TypeScript, and Jest for backend development and testing.
4. Proven experience with PostgreSQL and DynamoDB in large-scale environments.
5. Demonstrated ability to lead complex projects, manage technical roadmaps, and deliver high-quality software in a fast-paced setting.
6. Track record of mentoring engineers, building cohesive teams, and fostering a learning culture.
7. Excellent communication and collaboration skills, with the ability to engage across multiple teams and stakeholders.
8. Strategic mindset with the ability to make both tactical and long-term technical decisions.