Senior Software Engineer, Banking Activities

Since we opened our doors in 2009, the world of commerce has evolved immensely, and so has Square. After enabling anyone to take payments and never miss a sale, we saw sellers stymied by disparate, outmoded products and tools that wouldn't work together.

So we expanded into software and started building integrated, omnichannel solutions – to help sellers sell online, manage inventory, offer buy now, pay later functionality, book appointments, engage loyal buyers, and hire and pay staff. Across it all, we've embedded financial services tools at the point of sale, so merchants can access a business loan and manage their cash flow in one place. Afterpay furthers our goal to provide omnichannel tools that unlock meaningful value and growth, enabling sellers to capture the next generation shopper, increase order sizes, and compete at a larger scale

Today, we are a partner to sellers of all sizes – large, enterprise-scale businesses with complex operations, sellers just starting, as well as merchants who began selling with Square and have grown larger over time. As our sellers grow, so do our solutions. There is a massive opportunity in front of us. We're building a significant, meaningful, and lasting business, and we are helping sellers worldwide do the same.

The Role

As a Senior Software Engineer on the Banking Activities, you will help build and operate Square's shared financial data platform for Banking. We standardize how accounts, balances, and transactions are modeled and reported across products like checking, savings, cards, and lending. We power customer-facing balances, transaction histories, and statements with a focus on accuracy, traceability, and low latency.

Our work includes real-time data ingestion, event-driven processing, and scalable APIs that unify money movement and reporting experiences. We partner closely with product, risk, compliance, and finance to ensure clarity and trust in how funds are represented. This is high-scale, reliability-critical engineering with an emphasis on strong distributed systems, pragmatic data modeling, and measurable impact on sellers.

You Will

• Solve ambiguous, high‑risk, cross‑team challenges in financial reporting and ledgering, working directly in code and driving solutions end‑to‑end across the Banking stack.
• Guide the long‑term technical strategy for our reporting platform while contributing hands‑on to real‑time ingestion, balance computation, cross‑account linkage, and metadata systems.
• Partner with engineering, product, risk, compliance, and finance to shape consistent, auditable experiences for balances, transactions, and statements.
• Raise the technical bar through design reviews and architectural guidance; author designs for event‑driven pipelines, data models, and APIs; set high standards for correctness, reliability, observability, and extensibility.
• Mentor engineers to grow technical depth and leadership, fostering expertise in accounting fundamentals, distributed systems, and large‑scale data quality.
• Build a best‑in‑class financial data platform with robust APIs, clear documentation, and responsive support that enable product teams to deliver cohesive, low‑latency reporting while maintaining strong controls and auditability.

You Have

• 8+ years of backend engineering experience with proven organizational impact
• Expertise in Go, Ruby, or Kotlin with openness to learn others
• Proven track record of architecting and scaling high-reliability financial systems with high operational excellence, fault tolerance, and data integrity
• Strong mentorship, cross-team collaboration, and technical communication skills, with experience building trust across teams and functions
• Ability to decompose complex, ambiguous problems into maintainable solutions

Technologies We Use and Teach

• Services: Java, Kotlin, Go, Ruby on Rails
• Data: MySQL, DynamoDB, Kafka, SQS
• Infra: Protocol Buffers, Temporal, Terraform, Kubernetes, AWS