[Remote] Senior Full Stack Engineer, Client Platform

Note: The job is a remote job and is open to candidates in USA. PENN Entertainment, Inc. is a North American provider of integrated entertainment, sports content, and casino gaming experiences, with digital platforms powered by proprietary technology. PENN Interactive is seeking a Senior Full Stack Engineer to build and evolve shared client-platform tooling, React and TypeScript applications, and server-driven GraphQL services. The role includes designing APIs, improving performance and observability, partnering with product teams, mentoring engineers, and supporting scalable, accessible web experiences.

Responsibilities

• 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

Skills

• 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)
• 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
• 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
• A passion for sports or esports

Benefits

• Fun, relaxed work environment
• Education and conference reimbursements
• Opportunities for career progression and mentoring others
• Most non-sales positions are eligible for a Bonus.

Company Overview