Ostium is on a simple mission: make it possible for anyone with a digital wallet to trade stocks, commodities, currencies, and crypto with full transparency. No brokers, no freezes, no hidden spreads. We’re replacing the opaque, offshore brokerage model with a transparent, permissionless trading stack built onchain. Every trade, deposit, and withdrawal is verifiable through open, auditable code. We’ve raised $27.9M+ from General Catalyst, Jump, LocalGlobe, Susquehanna (SIG), GSR, Alliance DAO, Soma Capital, Balaji Srinivasan, Meltem Demirors, and others.

Role

We are looking for a Mobile Engineer proficient in Flutter and Dart to build our native mobile trading experience. You should have strong experience with BLoC for state management and be comfortable working in a Clean Architecture codebase.

Responsibilities

• Application Engineering: Develop high-performance, cross-platform mobile applications that deliver a native-tier experience on both iOS and Android

• Scalable Architecture: Architect scalable and testable codebases using Clean Architecture principles, enforcing strict separation of concerns and modular dependency injection.

• Architecture: Adhere to Clean Architecture or Feature-First patterns, maintaining a strict separation of concerns and utilizing Dependency Injection.

• Web3 Mobility: Integrate mobile-first Web3 features, including WalletConnect, Reown AppKit, or Privy for seamless on-the-go trading.

• Web3 Integration: Architect seamless mobile-first Web3 authentication and wallet connectivity, ensuring secure signing and transaction lifecycles on the go.

• Data Handling: Manage networking via GraphQL and REST, utilizing code generation (freezed/json_serializable) for immutable data models.

• Quality Assurance: Write comprehensive Unit and Widget tests to ensure stability across iOS and Android.

Requirements

• Core: Flutter 3.x, Dart, BLoC.

• Architecture: Proven experience with Clean Architecture/Feature-First patterns.

• Web3 Integration: Experience with web3dart, eth_sig_util, or similar Ethereum Dart libraries.

• Navigation: Experience with GoRouter.

Preferred Qualifications

• Previous experience in DeFi or trading platforms

• Understanding of perpetuals trading and RWA markets

• Contributions to open-source projects

• Experience with high-frequency trading systems or real-time data processing

• Understanding of perpetuals trading, RWA markets, and DeFi primitives.

• Experience with GraphQL Code Generator.

Benefits

• Competitive compensation package

• Opportunity to work with cutting-edge blockchain technology

• Collaborative environment with highly skilled team members

• Flexible work arrangements

• Professional development opportunities

This role is perfect for someone who is passionate about DeFi, enjoys working across the mobile technical stack, and wants to be part of building the future of on-chain RWA trading.

Interested candidates should submit their resume, GitHub profile, and any relevant project examples demonstrating their mobile stack expertise.