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Flutter Developer DeFi

KAST logo
KAST

KAST enables global spending of stablecoins through payment cards connected to traditional merchant networks and ATMs worldwide.

Hong Kong
About KAST

KAST lets users spend stablecoins at merchants worldwide through payment cards connected to traditional networks. The platform supports multiple stablecoins within a custodian wallet system. Users can create digital cards for immediate use with mobile payment systems or request physical cards in various tiers. The service operates in multiple countries to facilitate cross-border digital asset spending.

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Skills

About the Role

You will build and own consumer-facing DeFi features in the mobile app from end to end. You will turn lending, swap, and borrowing concepts into clear mobile experiences, integrate backend services, and manage secure transaction authorization, wallet, signing, and transaction-state flows. You will write maintainable, well-tested code, contribute to mobile architecture and shared components, participate in reviews and release quality, and work with product and design to deliver features.

Requirements

  • 2+ years of production mobile development with Flutter, or 3+ years owning shipped consumer apps.
  • Hands-on DeFi experience with on-chain protocols such as lending, borrowing, staking, swaps, or wallets.
  • Understanding of collateral, LTV, health factor, and gas and network fees.
  • Strong knowledge of Flutter state management, navigation, clean architecture, and dependency injection.
  • Experience consuming REST APIs, handling authentication tokens, and managing asynchronous multi-step transaction flows.
  • Understanding of mobile security practices, including secure storage, sensitive-data handling, and MFA flows.
  • Experience with Git-based workflows, code review, and App Store or Play Store releases.

Responsibilities

  • Build and own consumer-facing DeFi features in the mobile app end to end.
  • Translate DeFi concepts such as lending, swaps, and borrowing into clear, trustworthy mobile user experiences.
  • Integrate backend services and handle secure multi-step money-movement and transaction-authorization flows.
  • Manage wallet, signing, and transaction states with robust error handling and user feedback.
  • Contribute to a clean, well-tested mobile architecture and shared component patterns.
  • Write testable, maintainable code and participate in code reviews and release quality.
  • Collaborate with product and design to turn requirements into shipped features.