Lead JavaScript Engineer

JavaScript

Prosta 20, Warszawa

Spyrosoft

220 - 255PLN

Net per hour - B2B

Full-time

B2B

Senior

Hybrid

Tech stack

English

C1

JavaScript

master

Kafka

advanced

Node.js

advanced

TypeScript

advanced

Jest

advanced

PostreSQL

advanced

AWS

regular

Job description

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.

Published: 15.08.2025

Meet the company

Spyrosoft

Spyrosoft is an authentic, cutting-edge software engineering company, established in 2016. We have been included in the Financial Times ranking of 1000 fastest growing companies for three consecutive years: 2021, 2022 and 2023.

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