We are currently supporting one of our clients in the search for a Senior Software Engineer with a strong focus on Android SDK development (approx. 75%), complemented by experience in iOS (approx. 25%). This is not an app development role - the focus is on low-level SDK development for behavioral data collection and fraud prevention, integrated into millions of mobile apps worldwide. Location: Remote (Germany/Sweden) Start: ASAP Duration: Until March 2027 Workload: Full-time Contract Type: Freelance Responsibilities Develop and maintain high-performance Android SDKs with a focus on stability, efficiency, and security. Integrate SDKs into various mobile frameworks and platforms. Analyze and optimize memory usage, threading, and concurrency. Support iOS SDK development and maintenance. Collaborate with international teams and participate in code reviews. Tech Stack & Tools Android (Primary Focus): Java (10 years), Kotlin Jetpack Compose Android NDK, Gradle, CMAKE Android Studio, Emulators Systems-level programming, threading & concurrency iOS (Secondary Focus): Objective-C (5 years), SwiftUI Xcode, Xcode CLI, Apple Simulator Cross-Platform (Nice to Have): Cordova, React Native, Xamarin, Flutter, Ionic General: HTTP/Web communication CI/CD, Unit Testing, Source Control Your Profile Deep understanding of Android system architecture and SDK development. Experience with low-level programming and performance optimization. Willingness to contribute to iOS SDK development. Independent working style, strong team collaboration, and clear communication. If you're interested, please send an email including: Your earliest possible start date Your hourly rate expectations Your current CV in Word format A brief overview of relevant project experience Feel free to forward this opportunity to colleagues or contacts who might be a good fit. I look forward to hearing from you!