Software Engineer - Client Platform (Frontend/Backend)
Job Description
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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
- 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
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PENN Entertainment
View Company ProfilePENN Entertainment, Inc. (formerly known as Penn National Gaming) is the premier, enterprise-grade integrated entertainment pioneer, omnichannel sports content distributor, and digital gaming powerhouse engineered to operate as the definitive, high-velocity land-based casino and interactive iGaming layer across North America. The company completely eliminates the severe operational friction of traditional, siloed hospitality and wagering infrastructuresโwhere operators face fragmented customer retention metrics, separated retail-to-digital tracking loops, complex multi-jurisdictional compliance laws, and unoptimized gaming floor space configurationsโby deploying a unified, ecosystem-wide customer engagement matrix. Moving far beyond its 1970s origins as a regional thoroughbred racetrack operator, PENN Entertainment natively unifies 44 brick-and-mortar casino and racing destinations across 20 states, a state-of-the-art digital media and betting platform (ESPN BET and theScore Bet), an in-house digital game design studio (PENN Game Studios), and its industry-leading PENN Play customer loyalty engine into a single high-availability entertainment ecosystem. Publicly traded on the Nasdaq Stock Market (NASDAQ: PENN), the institution leverages its proprietary technology stack to serve over 25 million rewards members, seamlessly cross-selling premium physical resort experiences, Vegas-style table games, and real-time mobile sportsbooks with production-hardened precision. Under the hood, its sophisticated technical practice orchestrates high-concurrency transaction processing nodes, automated geo-fenced mobile betting frameworks, machine learning-driven customer personalization pipelines, and strict compliance-audited data networks matching rigid regulatory standards across dozens of legal gaming commissions. What sets PENN Entertainment apart is its uncompromising dedication to replacing legacy, standalone wagering with absolute, digital-first hospitality momentum; by bridging the gap between performance-intensive online betting engines and market-dominant physical resort footprints, the conglomerate remains the undisputed category-defining cornerstone of modern retail gaming and interactive sports entertainment.
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