Staff Frontend Engineer, Activation and Engagement Web (Growth)

Block is one company built from many blocks, all united by the same purpose of economic empowerment. The blocks that form our foundational teams - People, Finance, Counsel, Hardware, Information Security, Platform Infrastructure Engineering, and more - provide support and guidance at the corporate level. They work across business groups and around the globe, spanning time zones and disciplines to develop inclusive People policies, forecast finances, give legal counsel, safeguard systems, nurture new initiatives, and more. Every challenge creates possibilities, and we need different perspectives to see them all. Bring yours to Block.
The Role
The Activation and Engagement Web team is a critical part of Square's Growth Product organization, with a mission to help sellers start, run, and grow their businesses with Square. As part of the Growth strategy to Simplify, Automate, and Graduate seller experiences, we build and maintain the frontend experiences and supporting infrastructure that guide sellers from signup through their first payment and into ongoing product engagement.
We enable both end-to-end seller journeys and the platform capabilities that empower other teams to build exceptional web experiences-through shared components, frameworks, and extensible architecture. Our focus is on automating complex workflows and removing friction from key seller moments, with a direct impact on Square's growth initiatives.
We're looking for a Staff/Principal Frontend Engineer (L7) to serve as the technical authority for our team while remaining deeply hands-on. You'll drive cross-org architectural initiatives, set technical direction, implement key features, and mentor engineering talent across teams. This role blends strategic leadership with hands-on execution to shape the systems and experiences that power millions of seller interactions.
You Will

• Design and implement complex, user-facing features and frontend architectures that scale.
• Build and maintain Next.js and React applications with high standards for performance, maintainability, accessibility, and reliability.
• Lead org-wide engineering initiatives that impact seller acquisition, activation, and adoption - shaping critical user experiences.
• Define and drive the technical vision for the Activation Web platform, setting architectural direction and best practices across Growth orgs.
• Champion frontend reliability and operational excellence, including monitoring, testing, and incident response standards.
• Lead root-cause analysis and resolution of high-severity incidents, driving cross-team improvements.
• Drive the deprecation of legacy frameworks like Ember, helping modernize our stack.
• Prioritize and advocate for tooling and platform investments that improve developer velocity and system extensibility.
• Collaborate closely with product, design, mobile and backend teams to rapidly prototype and iterate on high-impact features.
• Mentor engineers across the org, fostering a culture of technical excellence, inclusion, and high-velocity execution.
• Explore and apply emerging technologies-including AI-assisted tooling-to improve engineering workflows and seller experience.
• Influence strategic product and technical direction by identifying risks, opportunities, and architectural tradeoffs.

You Have

• 12+ years of experience with JavaScript/TypeScript and modern web frameworks (React, Next.js).
• Significant experience with component libraries - building or maintaining at scale.
• Hands-on experience setting up and maintaining large-scale web applications with a substantial contributor base (dozens of active weekly contributors)
• A track record of delivering high-quality, performant, production-level user interfaces.
• Proven ability to lead large projects from start to finish, with strong collaboration, communication, and ownership.
• Deep experience in operational excellence and frontend system health, including leading SEV response and setting org-wide reliability standards.
• The ability to define technical north stars and serve as a culture carrier for engineering quality and inclusive collaboration.
• Curiosity about emerging technologies and a practical mindset for applying them in system design and workflow improvement.

Even Better

• Experience leading frontend architecture for platform-wide components or frameworks.
• Knowledge of A/B testing frameworks and experimentation platforms at scale.
• Strong understanding of business and growth metrics, and how they translate into engineering and UX strategy.
• Deep commitment to web accessibility and real-world experience implementing accessibility guidelines.
• Familiarity with component systems like Storybook.
• History of driving org-level technical migrations or architectural transformations.
• Background in high-scale consumer or B2B SaaS products focused on acquisition and activation.

Technologies We Use and Teach

• Languages: TypeScript/JavaScript (Primary), Java
• Frameworks & Core Technologies: Next.js, React, Ember, Svelte, Node.js
• APIs & Communication: gRPC, REST, Protocol Buffers, GraphQL
• Experimentation: Optimizely, LaunchDarkly
• Testing: Jest, Playwright

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 .
While there is no specific deadline to apply for this role, U.S. roles are typically open for an average of 55 days before being filled by a successful candidate. Please refer to the date listed at the top of this job page for when this role was first posted.
Block takes a market-based approach to pay, and pay may vary depending on your location. U.S. locations are categorized into one of four zones based on a cost of labor index for that geographic area. The successful candidate's starting pay will be determined based on job-related skills, experience, qualifications, work location, and market conditions. These ranges may be modified in the future.
To find a location's zone designation, please refer to this resource . If a location of interest is not listed, please speak with a recruiter for additional information.
Zone A:
$263,600 - $395,400 USD
Zone B:
$263,600 - $395,400 USD
Zone C:
$263,600 - $395,400 USD
Zone D:
$263,600 - $395,400 USD
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. Check out our other benefits at Block.
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.