Senior Polyglot Engineer

We’re building Klarna’s next-generation money movement engine — a cross-platform system enabling fast, secure, and seamless money transfers across markets, currencies (including crypto), and payment networks. This engine will be a native part of Klarna’s core consumer products and help the company evolve from a BNPL provider to a borderless neobank.

You’ll work alongside product, design, compliance, and other engineering teams to deliver high-performance financial experiences at global scale.

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.

Our process:

CV selection
Initial recruitment screening
Technical interview
Online logic test
Cultural fit interview

Tech stack:

Backend: Java, Python, Node.js, TypeScript, Express

Frontend (bonus): React, React Native

Databases: PostgreSQL, Redis, DynamoDB

Cloud & Infrastructure: AWS (Elasticache, Firehose), Docker, CI/CD

Monitoring & Logging: Datadog, Elasticsearch

Klarna-specific tools (nice to have): PACS, OPF, Klarna AuthN/AuthZ, routing layers

Requirements:

8+ years of experience in software development, with strong backend focus

Proficiency in Java, Node.js, Python, and TypeScript

Experience building scalable, fault-tolerant backend services and APIs

Familiarity with payment integrations, banking/crypto APIs, and compliance (KYC/AML)

Experience with PostgreSQL, Redis, and AWS services

Understanding of CI/CD pipelines and monitoring best practices

Bonus: experience contributing to frontend codebases using React or React Native

Bonus: Klarna ecosystem experience (payments flow, internal services)

Main responsibilities:

Design, implement, and maintain robust backend systems and APIs powering P2P and cross-border transfers

Own features end-to-end: from system architecture and development to deployment and monitoring

Integrate with external payment and banking APIs, ensuring secure and compliant transaction flows

Collaborate with Klarna-internal systems (payments, identity, customer support

(Optional) Contribute to frontend development for AI-enhanced money transfer interfaces, FX tracking, and transaction histories

Ensure high standards in observability, fault tolerance, and security

Mentor junior engineers and contribute to internal documentation and knowledge sharing

About Spyrosoft

Spyrosoft is an authentic, cutting-edge software engineering company, established in 2016. In 2021 and 2022, we were among the fastest growing technology companies in Europe, according to the Financial Times. We were founded by a group of tech experts with established backgrounds in software engineering, who created an ‘engineer-to-engineer’ workplace, powered by enthusiasm, fairness and authentic relationships. Having a unique offering, which bridge the gap between technology and business, we specialise in technology solutions for industry 4.0, automotive, geospatial, healthcare & life sciences, employee experience & education and financial services industries.