Square
Staff Software Engineer, Square Cards
Since 2009, Square has empowered merchants with integrated, omnichannel solutions—from payments to inventory, finance, and more. The Cards team owns the entire cardholder journey—activation, digital wallet integration, spend incentives, and rewards—helping sellers manage cash flow and grow their businesses.
Role Overview We are looking for a Staff Product Engineer to lead the technical strategy for personalizing and optimizing key seller moments through data, experimentation, and machine learning. This hands‑on, cross‑functional role includes collaborating closely with product managers, data scientists, ML engineers, designers, and analytics to build, measure, and iterate on new product hypotheses at scale.
What You’ll Do
Lead design and development of systems that drive seller engagement through incentives, onboarding, and spend experiences.
Build and scale experimentation frameworks for testing offers, activation flows, and cardholder behaviors across millions of users.
Partner with ML teams to integrate models that predict engagement and personalize incentives, rewards, or educational nudges.
Develop infrastructure and pipelines that enable fast iteration and statistically sound decision‑making.
Collaborate with design, product, and analytics to translate insights into production features that improve retention and satisfaction.
Mentor engineers across teams, raising the bar for experimentation quality, observability, and data‑driven development.
Set technical direction for how the Cards team measures, learns, and ships product changes efficiently and responsibly.
You Have
12+ years of engineering experience, including deep work in product‑facing or ML‑enabled systems.
A strong background in backend or full‑stack development using languages such as Java, Kotlin, Ruby, Go, or Python.
Experience building large‑scale experimentation or personalization systems (A/B testing, feature flagging, model integration).
Familiarity with modern ML workflows—training/inference pipelines, feature stores, real‑time scoring—and integrating them into production safely.
A track record of influencing product direction through data and experimentation rather than intuition.
Strong collaboration and communication skills; able to bridge engineering, product, and data to ship measurable impact.
Comfort working in tier‑0 critical environments where accuracy and trust matter.
Technologies we use
Backend: Java, Kotlin, Go, Ruby on Rails
Data & ML: Python, Airflow, Spark, Snowflake, TensorFlow, Databricks
Infra: Kubernetes, AWS, Terraform, Protocol Buffers, Temporal
Seniority level Mid‑Senior level
Employment type Full‑time
Job function Engineering and Information Technology
EEO Statement 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. We consider qualified applicants with arrest or conviction records in accordance with state and local laws and “fair chance” ordinances. We are committed to fair and inclusive interview experiences and will provide reasonable accommodations to disabled applicants.
Use of AI in Hiring We may use automated AI tools to evaluate job applications for efficiency and consistency. These tools comply with local regulations, including bias audits, and we handle all personal data in accordance with state and local privacy laws.
Contact Contact us at privacy@block.xyz with hiring practice or data usage questions.
Benefits Every benefit we offer is designed with one goal: empowering you to do the best work of your career while building the life you want. Remote work, medical insurance, flexible time off, retirement savings plans, and modern family planning are just some of our offering.
About us Block, Inc. (NYSE: XYZ) builds technology to increase access to the global economy. Each of our brands unlocks different aspects of the economy for more people. Square makes commerce and financial services accessible to sellers. Cash App is the easy way to spend, send, and store money. Afterpay is transforming the way customers manage their spending over time. TIDAL is a music platform that empowers artists to thrive as entrepreneurs. Bitkey is a simple self‑custody wallet built for bitcoin. Proto is a suite of bitcoin mining products and services. Together, we’re helping build a financial system that is open to everyone.
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Role Overview We are looking for a Staff Product Engineer to lead the technical strategy for personalizing and optimizing key seller moments through data, experimentation, and machine learning. This hands‑on, cross‑functional role includes collaborating closely with product managers, data scientists, ML engineers, designers, and analytics to build, measure, and iterate on new product hypotheses at scale.
What You’ll Do
Lead design and development of systems that drive seller engagement through incentives, onboarding, and spend experiences.
Build and scale experimentation frameworks for testing offers, activation flows, and cardholder behaviors across millions of users.
Partner with ML teams to integrate models that predict engagement and personalize incentives, rewards, or educational nudges.
Develop infrastructure and pipelines that enable fast iteration and statistically sound decision‑making.
Collaborate with design, product, and analytics to translate insights into production features that improve retention and satisfaction.
Mentor engineers across teams, raising the bar for experimentation quality, observability, and data‑driven development.
Set technical direction for how the Cards team measures, learns, and ships product changes efficiently and responsibly.
You Have
12+ years of engineering experience, including deep work in product‑facing or ML‑enabled systems.
A strong background in backend or full‑stack development using languages such as Java, Kotlin, Ruby, Go, or Python.
Experience building large‑scale experimentation or personalization systems (A/B testing, feature flagging, model integration).
Familiarity with modern ML workflows—training/inference pipelines, feature stores, real‑time scoring—and integrating them into production safely.
A track record of influencing product direction through data and experimentation rather than intuition.
Strong collaboration and communication skills; able to bridge engineering, product, and data to ship measurable impact.
Comfort working in tier‑0 critical environments where accuracy and trust matter.
Technologies we use
Backend: Java, Kotlin, Go, Ruby on Rails
Data & ML: Python, Airflow, Spark, Snowflake, TensorFlow, Databricks
Infra: Kubernetes, AWS, Terraform, Protocol Buffers, Temporal
Seniority level Mid‑Senior level
Employment type Full‑time
Job function Engineering and Information Technology
EEO Statement 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. We consider qualified applicants with arrest or conviction records in accordance with state and local laws and “fair chance” ordinances. We are committed to fair and inclusive interview experiences and will provide reasonable accommodations to disabled applicants.
Use of AI in Hiring We may use automated AI tools to evaluate job applications for efficiency and consistency. These tools comply with local regulations, including bias audits, and we handle all personal data in accordance with state and local privacy laws.
Contact Contact us at privacy@block.xyz with hiring practice or data usage questions.
Benefits Every benefit we offer is designed with one goal: empowering you to do the best work of your career while building the life you want. Remote work, medical insurance, flexible time off, retirement savings plans, and modern family planning are just some of our offering.
About us Block, Inc. (NYSE: XYZ) builds technology to increase access to the global economy. Each of our brands unlocks different aspects of the economy for more people. Square makes commerce and financial services accessible to sellers. Cash App is the easy way to spend, send, and store money. Afterpay is transforming the way customers manage their spending over time. TIDAL is a music platform that empowers artists to thrive as entrepreneurs. Bitkey is a simple self‑custody wallet built for bitcoin. Proto is a suite of bitcoin mining products and services. Together, we’re helping build a financial system that is open to everyone.
#J-18808-Ljbffr