Mobile Software Engineer (Swift+Rust)

FH Solutions is seeking a Mobile Software Engineer to build and evolve a decentralized mobile wallet powered by a deterministic Rust SDK. This role emphasizes Swift development with strong systems thinking and expertise working across Swift-Rust FFI boundaries.

• Collaborate with engineers to design, implement, and ship new wallet features
• Implement wallet features on top of a deterministic SDK, ensuring correctness and security across the full stack
• Improve mobile SDKs, including potential improvements to the foundational Rust SDK
• Work with AI-assisted development tools, critically evaluating and validating all generated code
• Improve continuous integration processes
• Debug and troubleshoot across stack boundaries (mobile, SDK, networking)

• 3+ years professional software engineering experience with significant production iOS development in Swift
• Strong understanding of deterministic state machines and ability to reason about correctness in financial or security-sensitive systems
• Comfortable working across language boundaries (Swift-Rust FFI) with understanding of memory ownership, threading, and error propagation
• Conceptual understanding of cryptographic primitives (hashes, signatures, key derivation, Merkle trees)
• Experience building mobile applications with complex local business logic or SDKs
• Strong debugging skills across stack boundaries
• Proficient with Git and modern collaborative workflows
• Strong Linux/macOS command-line skills
• Ability to work remotely in a self-directed environment
• Strong written and spoken English
• Comfortable reasoning about state, correctness, and security in adversarial environments
• Nice-to-have: Rust experience, Rust FFI experience, Android development, blockchain knowledge (UTXO vs account-based models), SPV or client-side transaction verification, cryptographic or privacy-preserving systems experience, distributed systems background

Schedule & Location: Remote position

Work Environment: Modern coding practices, team-oriented, operates without centralized backend, prioritizes client-side verification and security