Senior FullStack Engineer (NodeJS + React)

Our client: Klarna

Location: Warsaw (hybrid work: 2-3 days in the office)

Rate: 170 - 195 PLN per hour

Cooperation model: B2B or Employment Contract

Start date: ASAP

Duration: long-term agreement

Recruitment process: 1 timed Abstract and Logical Reasoning Test (up to 15 minutes); 1 short interview (up to 30 minutes)

Technology stack: JavaScript, TypeScript, Node.js, React, AWS, Docker, Redux, MongoDB, Firebase

Do you want to play a key role in revolutionizing the future of finance? Join Klarna - a global leader in deferred payments, with over 85 million active users and 2.5 million transactions processed daily! As a pioneer in modern payment solutions, Klarna is developing innovative methods that streamline the shopping experience, enhance transaction security, and expand the availability of purchasing options. 

We're seeking individuals eager to achieve remarkable results and share their bold vision to redefine the future of payments and fintech. Send us your CV - we can’t wait to meet you!

Your role is:

-> To be a key member of the team, actively shaping its culture and processes, including agile practices like pair and mob programming;

-> To use automated deployment tools to support frequent, daily code releases;

-> To collaborate with a team of skilled professionals, embracing success, failure, and shared learning to create a growth-oriented environment where failures are seen as educational steps toward innovation;

-> To make well-reasoned design decisions and address security, privacy, and compliance systematically.

Your skills and experiences:

-> 6+ years of experience in Javascript/Typescript;

-> Framework knowledge: React.js (front-end), Node.js (back-end), Redux, Context API, Hooks;

-> Tools: CI/CD experience, familiarity with npm/yarn, Webpack, Babel;

-> Databases: NoSQL (MongoDB, Firebase), SQL for backend systems with Node.js;

-> Cloud and DevOps: Familiarity with serverless architecture (e.g., AWS), experience with AWS services and infrastructure;

-> System Design Focus:

Frontend: scalability, performance, state management in React.js;

Backend: scalable, event-driven in Node.js;

-> Debugging & Testing: Approach to debugging, refactoring, clean and testable code;

-> Familiarity with CI/CD pipelines, automating workflows;

-> Experience with AWS services and cloud infrastructure;

-> Strong educational background in Computer Science, Information Technology, or a related field;

-> Experience in driving complex projects from start to finish, guiding and mentoring teams;

-> Experience in contributing to architectural design and system-wide decision-making with proven track record of both technical and organizational impact;

-> Language proficiency: Advanced English (minimum B2 level).

Nice to have:

+ Practical experience with TypeScript; 

+ Express, NestJS, NextJS, React Native;

+ GCP or Azure;

+ Docker for Node.js apps, third-party API integration (e.g., payment gateways, social login);

+ Experience in fintech, payments, startups, scale-ups, or streaming tech.

Our client offers:

+ Great opportunity for personal development in a stable and friendly large multinational company;

+ Start-up mentality, small agile teams;

+ Global Reach: Impact millions with seamless shopping and payments;

+ Career growth and additional education.