Senior Backend Engineer — Payments & Distributed Systems 12-month contract · Hybrid, downtown Toronto (3 days onsite) · T4

About the Role

We are looking for a Senior Backend Engineer to help design, build, and scale the core services powering a real-time payments and settlement platform at a major fintech. In this role, you will develop reliable, secure, and high-performance backend systems supporting payment processing, ledgering, transaction orchestration, reconciliation, and integrations with internal and external financial systems.

You will work closely with product, infrastructure, compliance, and partner integration teams to deliver systems that are resilient, auditable, and scalable. This is an ideal role for an engineer who enjoys solving complex distributed systems problems and has experience building backend services in highly regulated or transaction-heavy environments.

Responsibilities

• Design, build, and maintain backend services and APIs for payment initiation, transaction processing, settlement, reconciliation, and reporting
• Develop and maintain RESTful APIs and internal services using Python and FastAPI
• Model and manage transactional data in PostgreSQL, ensuring strong consistency, performance, and auditability
• Architect systems for idempotency, retries, fault tolerance, and observability across payment workflows
• Build integrations with banking partners, payment processors, custodians, and third-party financial platforms
• Collaborate with product and engineering teams to define technical solutions for new payment capabilities and operational workflows
• Improve system reliability, latency, scalability, and developer experience across backend services
• Implement robust testing strategies, including unit, integration, and end-to-end tests
• Participate in architecture reviews, code reviews, incident response, and operational readiness planning
• Contribute to engineering best practices around security, compliance, deployment, and monitoring
• Mentor other engineers and help raise the technical bar across the team

Required Qualifications

• 5+ years of professional software engineering experience, with significant backend or platform engineering work
• Strong proficiency in Python in production environments
• Hands-on experience building APIs and backend services with FastAPI or similar modern Python web frameworks
• Strong experience with PostgreSQL — schema design, indexing, query optimization, transactional integrity, and migrations
• Experience designing and operating distributed systems or event-driven architectures
• Experience building systems requiring strong reliability guarantees (payments, financial systems, or other transactional platforms)
• Solid understanding of: API design and service-to-service communication; authentication and authorization patterns; idempotency and concurrency control; background jobs, retries, and failure handling; monitoring, logging, and observability
• Experience working with cloud infrastructure and containerized environments
• Strong communication skills and ability to collaborate across engineering, product, and operations teams

Preferred / Nice to Have

• Experience building or operating payments, ledger, treasury, reconciliation, or other financial infrastructure systems
• Familiarity with Temporal.io or similar workflow orchestration platforms for long-running, fault-tolerant processes
• Experience integrating with banking APIs, payment gateways, custodians, or core financial systems
• Exposure to blockchain, digital asset, or stablecoin infrastructure
• Experience with event streaming, message queues, or asynchronous processing architectures
• Familiarity with security and compliance requirements in regulated environments
• Experience designing approval workflows, transaction controls, or operational risk systems

Technical Environment

• Languages/Frameworks: Python, FastAPI
• Database: PostgreSQL
• Infrastructure: Docker, cloud-native services, CI/CD pipelines
• Architecture: Microservices / distributed systems / event-driven systems
• Observability: Logging, metrics, tracing, alerting
• Optional: Temporal.io, blockchain infrastructure, custody/payment integrations

What You'll Work On

• Real-time settlement rails and payment orchestration services (internal transfers, blockchain-based settlement)
• Transaction lifecycle management — approvals, retries, reconciliation, and exception handling
• Ledger-adjacent services and financial state tracking
• Partner and bank integrations for payment execution and status monitoring
• Workflow automation for compliance, operations, and transaction processing
• Internal tooling and APIs for finance, support, and operations teams