Senior QA Engineer (f/m/d)

adjoe builds the technologies behind mobile apps growth and monetization. adjoe Ads is our programmatic in-app advertising platform that seamlessly connects advertisers and publishers through direct integration of our Android and iOS SDKs. Every ad decision happens in under 200ms across 10 million daily users, powered by real-time bidding algorithms and user quality prediction models that match the right ad to the right user at the right moment. Where 50 Billion Daily Predictions Begin The User Experience team is the origin point of adjoe Ads. Everything the system knows about a user, every prediction the ML models make, every bid placed in an auction. It all starts with code this team ships. The team owns two responsibilities. On the SDK side, a native Kotlin and Swift code runs inside hundreds of publisher apps. It participates in 120 million daily auctions , renders ad creatives across multiple formats, and captures the behavioral signals that power 50 billion predictions per day . The constraint that defines this work: you're executing inside someone else's app, on someone else's device, with zero tolerance for instability. Every ad impression has to feel native and fast to the user. On the analytics side, the dashboards, investigation tools, and data frameworks that turn raw data into decisions: real-time revenue performance across active campaigns, infrastructure cost visibility, and data quality assessments. If a number matters to the business or to engineering, this team makes it accessible. Your Mission & Who We Are Looking For: You have 3+ years in QA with hands-on mobile testing experience. You test more than UI flows, you dig into the full stack, from SDK behavior on device to the backend systems behind it, using tools like Kreya and k9s to investigate services, and Kibana and Grafana to monitor system health. You're comfortable working with AWS services and understand how container orchestration ( Kubernetes , Docker ), databases, and messaging systems ( Kafka , SQS ) behave under real conditions. You own testing end-to-end. You develop and execute comprehensive test strategies: regression, smoke, and beyond, and take ownership of post-release and post-implementation validation. You don't just report bugs, you understand the system well enough to know why they happen. You work closely with engineers, not just alongside them. You investigate how systems work, participate in feature requirement discussions, and contribute product-related insights based on your testing findings. You're comfortable reading and writing technical documentation. Automation is part of your toolkit. You have experience building and maintaining automated test suites ( Appium , Playwright ) alongside manual testing responsibilities. 🌎 We welcome applications from talent worldwide and provide relocation support to Hamburg, Germany for those ready to join our team. What’s in It for You? At adjoe, you’re not here to just close JIRA tickets, you’re helping build the infrastructure behind one of the most impactful platforms in adtech. The systems you work on will reach hundreds of millions of users and power billions of decisions every day. Go Big. Own projects with impact on 770M users and push adtech boundaries. Move Fast. Ship solutions multiple times a day, learn from results, and keep momentum. Be Direct. Solve problems openly and collaborate across teams. Thrive Together. Grow with a diverse, global team of people from over 40 different countries that learn from each other. Have Fun. Celebrate wins, enjoy daily victories, and bring your energy. We welcome applications from people who will contribute to the diversity of our company.