We're looking for a mid-level to senior Flutter engineer who understands DeFi — not just how to build a beautiful mobile app, but how DeFi products (lending, staking, swaps, savings, and self-custody wallets) actually work on-chain. You'll build consumer-facing DeFi products end to end, translating complex on-chain flows into interfaces that are clear, trustworthy, and delightful.
You'll collaborate closely with backend, product, and design to ship money-movement features that are secure and reliable.

Location: remote from the US.

Department: Engineering
Employment Type: Full Time
Location: New York
Workplace type: Fully remote

What You’ll Be Doing

Build and own consumer-facing DeFi features in the KAST mobile app, end to end.
Translate DeFi concepts (lending, swap, borrowing) into clear, trustworthy mobile UX.
Integrate with backend services and handle secure, multi-step money-movement and transaction authorization flows.
Handle wallet, signing, and transaction states — pending, submitted, confirmed, failed — 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 review and release quality.
Collaborate with product and design to shape requirements into shipped features.

What You'll Bring

2+ years of production mobile development with Flutter, or 3+ years with ownership of shipped consumer apps.
Hands-on DeFi experience is required — you have built, integrated, or worked closely with on-chain protocols (lending/borrowing, staking, swaps, or wallets) and understand concepts like collateral, LTV, health factor, and gas/network fees.
Strong command of Flutter fundamentals: state management, navigation, clean architecture, and dependency injection.
Experience consuming REST APIs, handling auth tokens, and managing complex asynchronous and multi-step transaction flows.
Solid understanding of mobile security best practices (secure storage, sensitive data handling, MFA flows).
Comfortable with Git-based workflows, code review, and shipping to the App Store / Play Store.

Nice to have

Experience integrating with DeFi lending, staking, or swap protocols on any major chain.
Familiarity with embedded/MPC wallet providers or self-custody / key import-export flows.
Experience in fintech, neobanking, or regulated financial products.
Exposure to mobile analytics/observability and CI/CD.
Contributions to shared Flutter packages or a modular multi-app codebase.

About KAST

KAST is redefining stablecoin banking for global citizens, crypto professionals, Web3-native businesses, and high-inflation markets hungry for USD-backed banking. Backed by top-tier global investors and led by the ex-APAC CEO of Circle, our leadership team spans Circle, Airwallex, Revolut, Wise, Grab, Zoom, AWS, and leading OTC desks. We’ve scaled from zero to nearly a million users at ridiculous speed.

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Frontend Developer (Flutter; DeFi)

Frontend Developer (Flutter; DeFi)

Skills

Description

What You’ll Be Doing

What You'll Bring

Nice to have

About KAST

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