Senior Staff Software Engineer

You own the backend systems and money paths for payments, payouts, deposits, transfers, and reconciliation. You design secure app-facing APIs and authentication services, integrate financial providers, trace on-chain settlement, and establish testing, documentation, correctness, and security standards for backend development.

Responsibilities

• Design and build backend systems for a high-usage consumer app
• Own versioned and backward-compatible app-facing API contracts
• Implement client idempotency keys, error models, and pagination
• Own authentication and authorization services
• Implement passkey and WebAuthn relying-party functionality
• Manage session and token lifecycles
• Enforce authorization at every API boundary
• Defend authentication services with rate limiting and anomaly detection
• Securely handle PII and secrets
• Set backend patterns, tests, and documentation
• Trace money paths through APIs, wallets, execution, indexing, event streams, and settlement
• Deliver test-first implementations of payment paths

Requirements

• Build and operate production backend systems that move real money
• Design client-facing APIs for mobile applications at scale
• Know API contracts, versioning, backward compatibility, idempotency keys, error models, pagination, and rate limiting
• Build authentication and authorization backends
• Know OAuth2, OIDC, JWT, RBAC, ABAC, MFA, and step-up authentication
• Integrate financial third parties and handle webhooks and reconciliation
• Understand on-chain settlement, nonces, gas, reorgs, RPC failures, and confirmation depth
• Use TypeScript or transition credibly from Go, Kotlin, Rust, or Java
• Use Postgres, event or queue systems, and gRPC
• Practice test-first, behavior-driven, and integration testing
• Use agentic development workflows