Senior Software Engineer - Payments & Treasury

Your Role

As a Senior Backend Software Engineer on our Payments team, you will architect, build, and scale mission-critical financial systems that form the foundation of Alpaca's global treasury platform. You'll be responsible for systems that process billions of dollars in transactions daily while ensuring financial integrity, regulatory compliance, and operational excellence.

Key Responsibilities:

• Design and implement robust, scalable payment processing systems that support ACH and SWIFT payment rails, with architecture capable of expanding to additional payment networks across multiple jurisdictions
• Architected and maintained financial ledger systems that enforced proper accounting principles,s including double-entry bookkeeping, balance sheet integrity, and transaction immutability
• Develop two-phase transfer mechanisms that ensure atomicity, consistency, isolation, and durability (ACID) in financial transactions
• Create automated reconciliation systems for transaction verification, account balancing, and error detection
• Implement financial controls,s including segregation of duties, approvals workflow, and audit trails
• Build and enhance settlement systems that maintain perfect financial record-keeping with complete audit history
• Design and implement secure, auditable APIs for internal and external payment services
• Contribute to technical decision-making for the payments infrastructure roadmap
• Mentor junior engineers and participate in code reviews to maintain high engineering standards

Technical Environment:

• Backend services primarily written in Go with a microservices architecture
• API services using gRPC for internal communication and RESTful interfaces for external systems
• Event-driven design patterns using message brokers for asynchronous processing
• PostgreSQL for transactional data with strong consistency requirements
• Kubernetes for containerization and orchestration on Google Cloud Platform
• Rigorous testing practices, including unit, integration, and end-to-end tests
• Continuous integration and deployment pipelines

Must-Haves:

• 5+ years of backend engineering experience with at least 3 years working with distributed systems at scale
• Strong expertise in Go, including production experience building and maintaining Go microservices
• Deep understanding of financial transactions, payment processing systems, and transaction safety
• Experience with ACH and SWIFT payment networks and their technical requirements
• Strong knowledge of financial accounting principles including:
• Double-entry accounting with debits and credits
• Trial balance reconciliation
• General ledger management
• Financial reporting and statement generation
• Transaction matching and exception handling
• Experience with two-phase commit protocols or similar transaction safety mechanisms
• Experience designing and implementing gRPC services and API gateways
• Proven experience with relational databases (preferably PostgreSQL) for financial record-keeping
• Experience working with distributed systems, eventual consistency, and event sourcing
• Strong system design skills with the ability to make architectural decisions and trade-offs
• Excellent problem-solving skills with a focus on reliability, security, and auditability

Nice-to-Haves:

• Experience with international payment processing systems and multi-currency infrastructure
• Knowledge of ISO20022 financial messaging standards and implementation
• Experience with banking APIs and integration with core banking systems
• Familiarity with financial regulations related to money movement, including AML/KYC requirements
• Understanding of regulatory frameworks for cross-border transactions
• Experience building financial systems that support multiple jurisdictions
• Experience mentoring engineers and providing technical leadership
• Prior experience in fintech, brokerage, or trading systems
• Experience with observability tools for distributed systems monitoring
• Knowledge of security best practices for financial systems