Senior Software Engineer

At OneSpan, we specialize in digital identity and anti-fraud solutions that create exceptional and secure experiences.

OneSpan is currently looking for a Sr. Software Engineer (Python) to join our team in Barcelona.

We are building an advanced Android application protection tool focused on APK/AAB transformation, code obfuscation, and native code integration. 

Our tooling analyzes and transforms Android applications at different levels, including bytecode and build artifacts, to implement protection and security mechanisms used in production mobile environments. 

We are looking for a senior engineer who can help us evolve the architecture, maintainability, and scalability of the platform while mentoring a growing engineering team. 

Job Duties and Responsibilities

• Design, develop, and evolve our Android protection tooling written primarily in Python.  


• Improve the architecture, modularity, reliability, and maintainability of the system.  


• Work on complex transformation pipelines involving APK/AAB processing and code manipulation.  


• Contribute to performance optimization and scalability of the tooling.  


• Write clean, testable, and production-quality code.  


• Improve testing strategies, CI/CD pipelines, release automation, and developer workflows.  


• Mentor junior engineers and help grow engineering best practices across the team.  


• Collaborate closely with Android and security engineers to design and implement new protection techniques.  


• Participate in technical discussions, code reviews, and architectural decision-making. 


• Design and develop our app protection tool using Python to support our platform and products. 


• Work on challenging architectural and performance problems, contributing to the evolution of our systems. 


• Write clean, maintainable, and testable code, ensuring high reliability and performance. 


• Collaborate closely with mobile developers, backend engineers, product managers, and designers to deliver well-architected solutions. 


• Improve the scalability, observability, and maintainability of our systems as the business grows. 


• Contribute to technical decision-making, code reviews, and architectural discussions. 

Requirements

• 5+ years of professional software engineering experience using Python.  


• Strong software architecture and system design skills.  


• Experience building complex applications, developer tooling, CLI applications, or transformation pipelines.  


• Strong understanding of software quality practices, testing, and maintainability.  


• Experience mentoring engineers or leading technical initiatives.  


• Ability to work autonomously on technically challenging systems.  


• Strong analytical and problem-solving skills.  


• Good communication skills in English. 

Nice to have:

• Interest or experience in security tooling, reverse engineering, or low-level systems.  


• Familiarity with Android internals, APK/AAB structure, or mobile application tooling.  


• Experience with bytecode manipulation, static analysis, or code transformation concepts.  


• Familiarity with Dalvik bytecode / smali.  


• Experience with Java or Kotlin.  


• Experience with reverse engineering or instrumentation tools such as JADX, apktool, Frida, Ghidra, or similar.  


• Experience working in Unix/Linux environments.  


• Experience with CI/CD pipelines and automated release systems.  


• Familiarity with Docker or containerized environments.  


• Knowledge of cryptography or application protection techniques. 

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