Kotlin Multiplatform Developer (Android/iOS)

Company Description

HODLER Group operates in the digital asset space, building and supporting platforms that make crypto trading accessible, secure, and user-friendly for a global audience. Compliance, security, and transparency sit at the centre of how we work. Our teams are technology-driven and value problem-solving, customer-centric thinking, and continuous improvement.

Role Description

The Junior–Mid Kotlin Multiplatform Developer is a full-time, hybrid role based in Athens, with the flexibility to work from home part of the time. This role is a great fit for someone with solid Kotlin foundations who wants to grow their cross-platform skills alongside experienced engineers.

Key Responsibilities

• Develop and maintain features across our Android and iOS apps using Kotlin Multiplatform (KMP), sharing business logic between platforms
• Build and extend shared modules for networking, data, and domain logic using coroutines, Flow, Ktor, and kotlinx.serialization
• Implement and refine UI with Jetpack Compose on Android, and contribute to iOS UI (SwiftUI or Compose Multiplatform)
• Integrate with REST APIs and WebSockets to deliver real-time prices, order books, and account data
• Apply mobile security best practices, including secure storage (Keystore/Keychain), biometric authentication, certificate pinning, and safe handling of sensitive user data
• Integrate third-party SDKs such as KYC/identity verification, payment providers, push notifications, and analytics
• Write and maintain automated unit and UI tests, and take part in code reviews
• Troubleshoot and resolve production issues using crash reporting and monitoring tools, and help identify performance bottlenecks
• Support the release process for Google Play and the App Store
• Collaborate with backend, product, design, and QA teams to deliver features end to end

Requirements

• 1–3 years of professional experience in mobile development with Kotlin
• Hands-on experience with Kotlin Multiplatform (professional or substantial personal projects), including shared modules and expect/actual declarations
• Solid command of Kotlin, including coroutines, Flow, and null safety
• Experience with Jetpack Compose and modern Android architecture (MVVM or MVI, ViewModel, dependency injection)
• Experience consuming REST APIs (JSON, HTTP, authentication methods such as JWT or OAuth)
• Working familiarity with the iOS toolchain (Xcode, basic Swift) sufficient to integrate and debug shared KMP code
• Experience with Git and Gradle
• Good understanding of mobile app security fundamentals
• Fluent in English, written and verbal
• Eager to learn, open to feedback, and able to take ownership of tasks with appropriate support

Nice to Have

• Experience with Compose Multiplatform on iOS or with SwiftUI
• Experience with mobile CI/CD (e.g., GitHub Actions, Fastlane, Bitrise)
• Apps published on Google Play and/or the App Store
• Basic understanding of crypto, blockchain, and digital asset trading
• Prior experience in fintech, banking, EMI, or payments environments

What We Offer

• Competitive Salary: €30000–€40000 gross, based on experience and qualifications
• Generous Leave Policy: Extra annual leave to support a healthy work–life balance
• Flexible Work Setup: Hybrid role with flexible hours
• Thrilling Industry Exposure: Be part of the fast-growing cryptocurrency sector
• Top-Quality Equipment: Access to modern tools and technology, including the Mac hardware needed for iOS development
• Growth and Mentorship: Work alongside experienced engineers and build deep cross-platform expertise