Senior Full Stack Engineer, Client Platform

PENN Interactive; United States; On-site; USD 135,000 - 180,000; Full time

Benefits offered by this job

Education and conference reimbursem

Career progression and mentoring

Job summary

PENN Interactive is hiring a senior software engineer in the United States to build and evolve GraphQL schemas, server-driven UI contracts, and scalable APIs across iOS, Android, and web clients. You will work with React and TypeScript to deliver fast, accessible experiences and partner with product/design on customer features.

You will also design monitoring and testing pipelines, own release cycles, and contribute to production reliability while mentoring teammates and driving architectural

Qualifications

• 5+ years of experience in software engineering.
• Strong JavaScript, TypeScript, and React, with real UX instincts.
• 2+ years designing and evolving GraphQL schemas for multi-client surfaces (iOS/Android/web).
• Fluency with HTML, CSS, and browser environment (DOM, platform APIs).
• Solid CS foundation: data structures, distributed systems, algorithms, software design.
• Experience with API development in Node or Bun, or similar server framework.
• Experience with Kubernetes and containers.
• On-call rotation experience and end-to-end release ownership.
• Clear writing; authored tech specs, runbooks, and design docs.
• Experience with testing frameworks: Jest or Vitest, and ExUnit/RSpec/pytest.
• Nice to have: Apollo Federation at scale, GraphQL APIs with Absinthe, mobile development, hexagonal architecture, domain-driven design, relational DBs.

Responsibilities

• Design and evolve GraphQL schemas in a federated graph for client surfaces.
• Develop, scale, and optimize GraphQL APIs, RPC endpoints, and SQL queries behind our web surfaces.
• Build front-end applications and shared libraries with React and TypeScript.
• Partner with product and design to architect and ship customer-facing features.
• Use observability tooling to diagnose issues and improve guest experience.
• Set up monitoring and alerting in DataDog for owned systems.
• Improve code quality by addressing technical debt and enforcing standards.
• Mentor teammates through code reviews and pairing.
• Write thorough tests and strengthen automated pipelines with QA.

Skills

JavaScript

TypeScript

React

GraphQL

Server-side APIs

Kubernetes

Testing frameworks

Git / GitHub

Tools

Node or Bun

Apollo Federation

CI/CD

SQL

DataDog

Job description

PENN Entertainment, Inc. is North America’s leading provider of integrated entertainment, sports content, and casino gaming experiences. From casinos and racetracks to online gaming, sports betting and entertainment content, we deliver the experiences people want, how and where they want them. We’re always on the lookout for those who are passionate about creating and delivering cutting-edge online gaming and sports media products. Whether it’s through Hollywood Casino, theScore Bet Sportsbook, or theScore media app, we’re excited to push the boundaries of what’s possible. These state-of-the-art platforms are powered by proprietary in-house technology, a key component of PENN’s omnichannel gaming and entertainment strategy. When you join PENN Entertainment’s digital team, you’ll not only work on these cutting-edge platforms through theScore and PENN Interactive, but you’ll also be part of a company that truly cares about your career growth. We’re committed to supporting you as you expand your skills and explore new opportunities. With locations throughout North America, you can build a future at PENN Entertainment wherever you are. If you want to challenge conventions in gaming, media and entertainment, we want to talk to you. About The Team The Client Platform team's job is to make product teams fast. We own the shared component libraries and design system, the build and release tooling every engineer touches daily, and the performance, accessibility, and observability standards that hold across our client surfaces. Much of the work is internal tooling that keeps a large monorepo pleasant to work in. We partner closely with product teams to make the right thing the easy thing. The team also builds our server-driven UI service, a TypeScript GraphQL subgraph that lets product teams change what the iOS, Android, and web clients render without shipping an app release. The role spans both the monorepo and that service, so it is a genuine mix of front-end and backend GraphQL work. About The Work We Offer Design and evolve GraphQL schemas in a federated graph, including the server-driven UI contracts our mobile and web clients render. Treat those schemas as a versioned contract shared with released mobile apps: classify breaking changes, coordinate migrations with the iOS, Android, and web leads, and keep generated client models in sync. Develop, scale, and optimize the GraphQL APIs, RPC endpoints, and SQL queries behind our web surfaces. Build front-end applications and shared libraries with React and TypeScript. Build web applications that are fast and accessible to everyone. Partner with product and design to architect and ship customer-facing features. Use observability tooling to diagnose issues and improve the experience for guests. Set up and refine monitoring and alerting in DataDog for the systems you own. Improve code quality by finding technical debt, proposing fixes, and holding the standard for the whole team. Find bottlenecks and areas of risk in production, and drive the changes that make the platform scale. Learn from and mentor teammates through code review, pairing, and writing things down. Take part in the design, architecture, and delivery of new features in a collaborative agile team. Write thorough tests for every feature and bug fix. Testing is a first-class discipline on this team. Work with QA to strengthen automated testing pipelines and CI/CD workflows. Use Claude Code in daily development to move faster without lowering the bar. Other duties as required. About You At least 5 years of experience in software engineering. Strong JavaScript, TypeScript, and React, plus real instincts for UX. 2+ years designing and evolving GraphQL schemas for product surfaces used by multiple clients (iOS, Android, web). This sits at the center of the server-driven UI work, so it matters more here than in a typical front-end role. Fluency with HTML, CSS, and the browser environment: DOM, events, platform APIs. A solid foundation in computer science, with strong competencies in data structures, distributed systems, algorithms, and software design. A grasp of production systems at scale, including finding weak points through load testing and tracing. Experience investigating and fixing production performance regressions, including CPU hotspots and latency in high-throughput services. Experience on an on-call rotation for a production service, and owning release cycles end to end. You care about clean architecture and about code you will not mind reading a year from now. Clear writing. You have authored tech specs, runbooks, and cross-team design docs that stood up to scrutiny. Experience with API development in Node or Bun, or in another server framework (Phoenix, Ruby on Rails, FastAPI, Laravel). Experience building and integrating multi-client or white-label platforms, including geo-based routing and per-brand configuration. Experience with Kubernetes and comfort operating services in containers. Comfortable working in the terminal, with Git and GitHub or similar, and in an editor of your choice. Experience with testing frameworks: Jest or Vitest, and ExUnit, RSpec, or pytest. Nice to have: Apollo Federation at scale, GraphQL APIs with Absinthe, Mobile Development for iOS or Android using Swift or Kotlin, hexagonal architecture, domain-driven design, relational databases (PostgreSQL, MySQL), background job processing (Oban, Exq, Sidekiq, Celery), asynchronous event infrastructure (Kafka, RabbitMQ, SQS/SNS, Pub/Sub), open source contributions, startup experience, and a passion for sports or esports. What We Offer Competitive compensation package Fun, relaxed work environment Education and conference reimbursements. Opportunities for career progression and mentoring others. Salary Range $135,000—$180,000 USD Penn Interactive is proud to be an equal opportunity workplace. We will consider all qualified applicants for employment without regard to race, color, religion, age, sex, sexual orientation, gender identity, national origin, disability, veteran status, genetic information, or any other basis protected by applicable law.Base pay is one part of the Total Rewards that Penn Interactive provides to compensate and recognize employees for their work. Most sales positions are eligible for a Commission under the terms of an applicable plan, while most non-sales positions are eligible for a Bonus. Additionally, Penn Interactive provides best-in-class benefits to eligible employees. We believe that benefits should connect you to the support you need when it matters most, and should help you care for those who matter most. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality – to help support you physically, financially and emotionally through the big milestones and in your everyday life.