Staff Software Engineer, Activation & Engagement (Growth)

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.

About the Role

The Activation and Engagement Server Team is a core part of Square's Growth Product org, focused on helping more sellers use Square more effectively. Aligned with our strategy to Simplify, Automate, and Graduate seller experiences, we build and maintain backend systems that guide sellers from signup to first payment and into ongoing product engagement. Our work directly supports Square's growth by improving onboarding, engagement, and seller success.

We power onboarding flows across web, point of sale, and international surfaces through scalable, extensible APIs. Our focus is on automating complex workflows and removing friction from critical seller moments across the entire journey—from acquisition to activation and engagement. We're seeking a Staff Backend Engineer to be the technical lead for our platform. In this role, you'll combine strategic technical leadership with hands-on coding, driving architectural initiatives, building key platform features, and mentoring engineers across teams as we scale Square's growth infrastructure.

Open to US Remote locations

You Will

• Lead by example through hands-on development of critical architecture components while defining and driving the technical vision for Square's activation and engagement funnel improvements, establishing patterns and practices that shape experiences across multiple Growth Product teams through direct code contribution and mentoring.


• Drive activation and engagement funnel improvements by designing and building highly available backend services that power critical seller experiences, including setup guides, onboarding checklists, automated workflows, and engagement features


• Build and serve as the technical authority for scalable distributed systems to handle millions of seller interactions across web, POS, and international platforms while maintaining high reliability SLOs


• Lead organizational-level technical initiatives spanning Growth Product and beyond, setting the technical trajectory for activation infrastructure used by web, mobile, point of sale, and international teams


• Mentor and coach Staff and Senior engineers across the organization, fostering a culture of engineering excellence, learning, and inclusion beyond your immediate team


• Influence strategic product and technical decisions, proactively identifying risks and opportunities that affect the direction of Growth Product


• Enable extensibility and automation by building systems that outside engineers can easily understand, diagnose, and extend, supporting Growth Product's principles of rapid iteration and empowerment.


• Champion and implement reliability, monitoring, and operational standards for backend systems across the Growth Product organization


• Drive critical platform migrations and architectural evolution (e.g., service decomposition, data model unification, SLO strategy) with organizational impact

You Have

• 12+ years of backend/server engineering experience with proven technical and organizational impact at scale.


• Deep expertise in Java and/or Kotlin within the JVM ecosystem, with extensive hands-on experience in backend and platform systems at scale.


• Recognized authority in backend distributed systems with a strong track record of architecting scalable, reliable, and maintainable solutions across organizations.


• Demonstrated leadership in large-scale architectural initiatives, platform transformations, and technical migrations.


• Ability to break down complex, ambiguous problems into visionary, actionable solutions executed across multiple teams.


• Strong interpersonal and influencing skills, with experience mentoring engineers, coaching seniors, and building technical bench strength across teams.


• Deep experience driving operational excellence, including SEV response leadership, org-wide reliability practices, and CI/CD adoption.


• Experience defining technical strategy, setting engineering standards, and serving as a culture carrier for quality and inclusive collaboration.


• Proficiency with modern cloud infrastructure (e.g. AWS, Kubernetes, containerization) and automation at scale.


• Domain experience in onboarding/activation, user engagement, payments, or high-scale consumer/B2B SaaS platforms.


• Familiarity with A/B testing frameworks, experimentation platforms, and workflow orchestration systems used across teams

Technologies We Use and Teach

• Languages: Java(primary), Kotlin


• APIs & Communication: gRPC, REST, Protocol Buffers


• Frameworks: Guice, Hibernate


• Experimentation: Optimizely, LaunchDarkly.


• Testing: JUnit, Mockito, integration testing frameworks


• Platform & Architecture: Service mesh, distributed tracing, organizational monitoring strategies

We're 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 we're doing to build a workplace that is fair and square? Check out our I+D page .