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Wittix is a licensed Lithuanian electronic money institution building the financial platform companies use instead of a bank: multi-currency accounts, real local IBANs across Europe, payments in 35 currencies, and Visa cards with spend controls built in.
Our mobile app isn't a companion to a web dashboard. It's where our customers run their money. Around 2,400 businesses in 23 countries move roughly €120M a month through us. Bank payments is the first layer; a much wider set of payment services is coming, and mobile is where most of it will land.
We are looking for a strong Kotlin Multiplatform Engineer to join our mobile engineering team and help shape the architecture of the next generation of Wittix products.
This is an opportunity to have a direct impact on the architecture of a real world platform combining Kotlin Multiplatform, payments, AI, commerce, hardware, cloud infrastructure, and real time systems.
You don't need to have built a banking app before, but you should want to work somewhere correctness matters.
What you'll do
Design and develop production applications using Kotlin Multiplatform
Own and evolve the shared KMP architecture across the product
Define clear boundaries between shared KMP code and platform-specific implementations
Develop platform-specific integrations for Android and other supported platforms
Implement authentication and payment authorization flows, including in-app approval of card payments (3-D Secure)
Build card features against our issuing processor's APIs: activation, freeze, spend controls, Google Pay and Apple Pay
Build real-time experiences connected to cloud services and event-driven backend systems
Apply mobile security fundamentals: secure key storage, certificate pinning, device and app integrity checks
Establish reusable libraries and engineering patterns for KMP development
Debug complex production issues across shared and native code
Collaborate closely with Backend, Product, QA, DevOps
Participate in architectural decisions and technical design
Requirements
4+ years of professional mobile development, mostly Android
Strong Kotlin, including Coroutines and Flow
Strong hands-on experience with Kotlin Multiplatform, shipped to production
Strong understanding of modular architecture and the split between shared and platform-specific code
Experience with REST APIs and local persistence (SQLite / Room or equivalent)
Clean, testable architecture and meaningful tests
Enough Swift to read, debug and ship changes in an iOS codebase — or a clear appetite to get there quickly
Ability to make pragmatic architectural decisions in a real product
Working English.
Nice to have
Banking, wallet, payments, or another regulated consumer app
Card issuing or issuer-processor APIs
Mobile CI/CD (continuous integration and delivery): signed builds, TestFlight and Play internal tracks
Why Join Wittix
You'll shape a Kotlin Multiplatform architecture on a live product, not a prototype. Real money, real customers, and the authority to decide what belongs in the shared layer.