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Senior Javascript Developer
  • Warsaw
Senior Javascript Developer
Warszawa, Warsaw, Masovian Voivodeship, Polska
WINGED IT SP Z O O
6. 3. 2025
Informacje o stanowisku

Senior Javascript Developer

Miejsce pracy: Warszawa

Technologies we use

Expected

  • JavaScript
  • React.js
  • Node.js
  • AWS

Optional

  • NestJS
  • Raect Native
  • Google Cloud Platform
  • Microsoft Azure
  • Docker
  • MongoDB
  • Firebase
  • SQL
  • NoSQL

Operating system

  • macOS

About the project

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.

Were 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!

Our client: Klarna

Location: Warsaw (hybrid work 2-3 days a week from office)

Duration: long-term agreement

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

Your responsibilities

  • 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 take ownership of features end-to-end, manage incidents, and drive continuous improvement;
  • To make well-reasoned design decisions and address security, privacy, and compliance systematically.

Our requirements

  • Core Language: 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;
  • Language proficiency: Advanced English (minimum B2 level).

Optional

  • Practical experience with TypeScript;
  • Express, NestJS, NextJS, React Native;
  • GCP or Azure;
  • Architecture discussions for scalable, maintainable systems for senior engineers;
  • 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.

Division of working time

  • 80% New functionalities
  • 8% Meetings
  • 8% Documentation
  • 4% Testing

This is how we organize our work

This is how we work

  • at the clients site
  • you focus on a single project at a time
  • you have influence on the choice of tools and technologies
  • you have influence on the technological solutions applied
  • you have influence on the product
  • you focus on product development
  • agile

This is how we work on a project

  • code quality measures
  • code review
  • design patterns
  • Continuous Deployment
  • Continuous Integration
  • team-level deployment
  • documentation
  • issue tracking tools
  • technical debt management
  • test automation

Development opportunities we offer

  • industry-specific e-learning platforms
  • intracompany training
  • mentoring
  • space for experimenting
  • technical knowledge exchange within the company
  • time for development of your ideas

What we offer

  • 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.

Benefits

  • remote work opportunities
  • flexible working time
  • integration events

Recruitment stages

  • 1 initial interview (30-40 min)
  • 1 timed Abstract and Logical Reasoning Test (15 min)
  • 1 short interview (30 min)

WINGED IT SP Z O O

Winged IT is a Polish Tech Recruitment, Outstaffing, and Consulting Company with over 100 clients from 4 continents.

We deliver Tech Talents from Central and Eastern Europe, ready to work remotely from Poland or relocate to other countries.

We effectively support international companies in establishing their remote (in-house or oustaffed) engineering teams in Poland – to learn why to choose Poland, please visit our dedicated website https://doITinPoland.com/.

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