Staff Software Engineer, Square Cards

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 wouldnt 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 weve 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. Were building a significant meaningful and lasting business and we are helping sellers worldwide do the same.

The Role

Square empowers small businesses to thrive and the Square Debit Card is at the heart of that mission. Sellers use it every day to pay vendors cover payroll and reinvest in their growthknowing they can access their money instantly. The Cards team builds the systems and experiences that make this possible: activation experiences that feel effortless digital wallet integrations that feel seamless rewards that build loyalty and resilient platforms that sellers trust with their livelihoods.

As a Staff Software Engineer youll help define the future of how sellers access and spend their money. Youll take on some of the hardest engineering problems in fintechbalancing scale iteration and simplicitywhile shaping systems that other teams across Square and Cash will rely on. This is a hands-on role with org-wide impact: youll write code set technical direction and mentor senior engineers all in service of building financial tools that millions of businesses depend on every day.

You Will

• Define the technical vision for seller-facing card systems from activation and onboarding to incentives and account management ensuring they scale across geo markets and teams.
• Drive integrations that make Square Cards effortless to use across digital wallets third-party platforms and card-on-file experiences throughout the Square ecosystem.
• Architect resilient frameworks with robust fallback and failover paths setting standards for reliability across Banking.
• Build shared infrastructure for incentives and rewards enabling product teams to experiment and deliver long-term seller engagement at scale.
• Mentor senior engineers shaping design practices and codifying standards for reliability security and scalability.
• Partner with product design ML risk and compliance leaders to deliver trusted financial experiences that advance Squares mission globally.

You Have

• 12 years experience building and scaling large distributed systems.
• A track record of setting technical direction and delivering impact across multiple teams.
• Expertise in backend engineering (Java Kotlin or similar) with the ability to quickly learn new stacks.
• Experience designing frameworks and platforms that others rely on.
• A history of mentoring senior engineers and raising the technical bar for entire teams.
• Strong communication skills and the ability to align technical decisions with business priorities.
• A drive to build resilient trustworthy systems in high-stakes domains like payments or fintech.
• A mindset that balances fast iteration with building for the long term.

Technologies We Use and Teach

• Backend: Java Kotlin
• Data: MySQL DynamoDB Kafka SQS
• Infra: Kubernetes AWS Terraform Protocol Buffers Temporal
• Clients: TypeScript React Native Swift Kotlin

Were working to build a more inclusive economy where our customers have equal access to opportunity and we strive to live by these same values in building our workplace. Block is an equal opportunity employer evaluating all employees and job applicants without regard to identity or any legally protected class. We will consider qualified applicants with arrest or conviction records for employment in accordance with state and local laws and fair chance ordinances. We believe in being fair and are committed to an inclusive interview experience including providing reasonable accommodations to disabled applicants throughout the recruitment process. We encourage applicants to share any needed accommodations with their recruiter who will treat these requests as confidentially as possible. Want to learn more about what were doing to build a workplace that is fair and square Check out our ID page.