Lead Engineer — Application Security

Overview

In this Lead Engineer role within Klarna’s Secure Development team you help design and deliver secure software. You’ll influence architecture decisions, model threats, and drive security improvements across engineering teams. You’ll combine upstream security work with hands-on assessments, including code reviews and penetration testing, plus build tooling that makes secure practices easy to adopt. This is an opportunity to shape how Klarna ships resilient products at scale. You’ll work in a security-focused culture that values pragmatic, impact-driven engineering.

Responsibilities

• Perform threat modeling for new architectures and designs
• Review architecture and design decisions to harden applications and services
• Drive security improvements with engineering teams
• Build and enhance security tooling, automation, and processes
• Conduct security assessments including code reviews and penetration testing
• Contribute to Klarnas internal engineering security community

Key requirements

• Experience with security assessments (code reviews, penetration testing)
• Proficiency in at least one language: JavaScript (NodeJS), Python, Go, Erlang, Java, or Scala
• Broad knowledge across web/mobile/network security, OS hardening, cryptography, and cloud computing; expert in at least one
• Working proficiency in English
• Strong communication skills to explain security tradeoffs to non-security engineers
• Pragmatic problem solving
• Cross-functional collaboration
• Clear communication of security tradeoffs
• Threat modeling
• Architecture and design reviews
• Security tooling and automation

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