• Build and ship native Android features for onboarding, accounts, cards, payments, transfers, rewards and AI-assisted user journeys. • Turn complex financial flows into simple, fast and reliable mobile experiences. • Work closely with product, design, backend and AI engineers to take features from idea to production. • Own app quality across performance, crash rate, loading states, edge cases and release stability. • Use production feedback, analytics and customer behaviour to improve what you build after launch. • Integrate APIs, authentication, secure data handling and financial workflows with strong attention to reliability.

• Build and ship native Android features for onboarding, accounts, cards, payments, transfers, rewards and AI-assisted user journeys. • Turn complex financial flows into simple, fast and reliable mobile experiences. • Work closely with product, design, backend and AI engineers to take features from idea to production. • Own app quality across performance, crash rate, loading states, edge cases and release stability. • Use production feedback, analytics and customer behaviour to improve what you build after launch. • Integrate APIs, authentication, secure data handling and financial workflows with strong attention to reliability.

Role Description We are looking for an experienced Senior Mobile Ad Monetization Engineer to build, optimize, and maintain the advertising infrastructure across our client's Android applications. This is a hands-on position focused on developing high-performance ad delivery systems, improving SDK integrations, reducing latency, and maximizing advertising revenue. You will work closely with product, backend, analytics, and AI teams to deliver scalable monetization solutions without compromising the user experience. - Design, develop, and maintain the mobile advertising infrastructure. - Integrate and manage multiple mediation SDKs, including AppLovin MAX, Google AdMob, and Unity LevelPlay. - Develop advanced ad loading, caching, preloading, and request management mechanisms. - Optimize key monetization metrics: Fill Rate, Match Rate, Show Rate, Impression Rate, eCPM, and overall revenue. - Build intelligent ad selection, placement logic, and Remote Config fallback systems. - Optimize memory usage, threading, lifecycle management, and SDK initialization performance to reduce crashes, ANRs, and latency. - Build internal debugging, logging, and telemetry tools, alongside A/B testing infrastructure. - Collaborate with backend engineers on server-driven monetization. Qualifications - 5+ years of commercial Android development experience. - Strong programming skills in Kotlin and Java. - Deep understanding of the Android SDK and app lifecycle. - Proven experience integrating mediation platforms (AppLovin MAX, AdMob, Unity LevelPlay, or Google Ad Manager). - Experience optimizing ad loading performance, latency, and multithreading. - Familiarity with Firebase, Remote Config, Analytics, Crashlytics, and BigQuery. - Experience with REST APIs and backend-driven configurations. Requirements - Nice to have: Custom mediation adapters, RTB (Real-Time Bidding), server-driven monetization, AI-based optimization, and CI/CD. Benefits - Salary: €4,600 - €7,000 per month, depending on experience. - Type of work: 100% remote. - Contract type: B2B contract (invoicing Optiveum Poland). - You will own critical, revenue-generating infrastructure in a profitable startup. - Full remote flexibility and the chance to build technology used by millions.

Role Description Our client is a leading technology provider in the retail industry, delivering modern point-of-sale and store operations solutions to retailers across multiple markets. As part of an ongoing platform modernization initiative, they are evolving their client architecture away from a legacy Java 8 Swing-based POS client toward a modular, offline-first, multi-platform model — supporting stationary POS terminals, self-checkout kiosks, and self-scanning devices across diverse retail environments. The shared business logic layer is built with Kotlin Multiplatform (KMP), targeting both JVM/Desktop and Android clients. This layer is the heart of the platform: it owns the domain rules, use cases, and data flows for critical retail operations — item registration, checkout, payment, customer management, and promotion handling — while remaining fully decoupled from platform-specific concerns and UI. Business continuity through offline operation, high testability, and performance under real retail conditions are non-negotiable priorities. We are looking for a Senior Kotlin Developer who is experienced in KMP delivery, comfortable owning complex shared modules in a layered architecture, and motivated by the challenge of building the reliable, platform-agnostic foundation that modern retail operations depend on. Qualifications - 5+ years of experience with Kotlin, including strong hands-on KMP delivery to at least two targets (preferably Android and JVM/Desktop) - Solid understanding of Clean Architecture: domain, use-case, infrastructure, and platform layers with dependency inversion and repository abstractions - Practical experience with Kotlin Coroutines and Flow: structured concurrency, suspend APIs, Flow-based state and events, cancellation, and error propagation - Experience with offline-first or local-first client architecture: local persistence, caching, synchronization concepts, and conflict handling - Familiarity with dependency injection patterns, preferably Koin: constructor injection, module composition, and test overrides - Strong testing discipline: unit and integration tests using Kotlin Test or equivalent, test doubles, and coroutine testing utilities - Experience integrating REST/OpenAPI-style services: typed DTO mapping, serialization, and resilient client-side communication - Comfortable with Gradle Kotlin DSL, modular builds, and CI-friendly project structures - Effective communication skills for collaboration with frontend developers, QA, and product stakeholders Requirements - Design, implement, and maintain shared KMP modules for POS business capabilities, ensuring code is high-quality, maintainable, and performant across JVM/Desktop and Android targets. - Define clean repository, service, facade, DTO, and bridge contracts between Kotlin, platform-specific code, and the VueJS/TypeScript UI layer. - Implement platform-specific code for desktop and Android targets using expect/actual patterns, without leaking platform concerns into shared business logic. - Build offline-capable flows with local persistence, caching, synchronization readiness, and explicit failure handling. - Write clean, well-structured code, participate in reviews, and improve existing modules through refactoring where needed. - Write automated tests for domain rules, use cases, repositories, bridge contracts, and coroutine-based flows. - Work closely with frontend engineers, QA, product owners, and architects to align on contracts, requirements, and feature delivery. - Support teammates by sharing knowledge and mentoring less experienced Kotlin developers when appropriate. - Respect team agreements and processes, while providing regular updates on progress, trade-offs, and technical decisions. Benefits - Enjoy our holistic benefits program that covers the four pillars that we believe come together to support our wellbeing, covering social, physical, emotional wellbeing, as well as work-life fusion. - Physical Wellbeing: Our wellbeing program includes medical benefits, gym support, and personalized fitness options for an active lifestyle, complemented by team events and the Healthy Habits Club. - Work-Life Fusion: In very dynamic industries such as IT, the line between our professional and personal lives can quickly become blurred. Having a one-size-fits-one approach gives us the flexibility to define the work-life dynamic that works for us. - Emotional Wellbeing: We believe that to maintain our overall health, we need to invest in our mental wellbeing just as much as we do in our physical health, social connections or in achieving work-life balance. - Social Wellbeing: As a growing community in a hybrid environment, we want to ensure we remain connected not just by the great work we do every day but through our passions and interests.