Lead Engineer — Application Security

Location: Stockholm, London, Milan, or Warsaw

Salary: £91,196–£116,438 per year

Company

Klarna is building an everyday finance network used by more than 120 million consumers across 26 countries.

What you will do

• Perform threat modeling and architecture and design reviews for applications and services.
• Work directly with engineering teams on architectural decisions and security improvements.
• Build and continuously improve security tooling, automation, and development processes.
• Assess Klarna services through code reviews and penetration testing.
• Contribute to the internal engineering security community.

Requirements

• Proficiency in several areas including web application security, mobile application security, network security, operating system hardening, applied cryptography, and cloud computing, with expert-level knowledge in at least one area.
• Experience writing and reviewing code in at least one of JavaScript, NodeJS, Python, Go, Erlang, Java, or Scala.
• Pragmatic approach to identifying security issues, assessing risk, and implementing practical fixes.
• Working proficiency in English.
• Ability to analyze complex systems and explain security trade-offs to engineering stakeholders.

Nice to have

• Experience with BugBounty programs or CTF competitions.
• Security experience from non-traditional or self-taught backgrounds.

Culture & Benefits

• Cross-functional work across Klarna's engineering division rather than within a single product team.
• Hands-on involvement in secure software development and security-focused engineering practices.
• Applications should include a CV in English focused on concrete examples of work delivered, impact, and cost.