Senior Mobile Engineer - Kotlin

Location: United Kingdom; Remote

Senior Mobile Engineer - Kotlin (Full-Stack) Overview

As a Senior Software Development Engineer, Mobile at Fanatics Betting & Gaming (FBG), you are a senior individual contributor with strong Kotlin expertise and a passion for building modern, scalable mobile experiences. While mobile development remains core to this role, we are specifically looking for engineers who can operate across the full stack,  contributing to both client applications and the backend systems that power them.

You bring deep experience with Kotlin (or Java), Jetpack Compose, and modern Android architecture, alongside hands-on experience building or contributing to backend services in distributed systems. You are comfortable working on Backends for Frontends (BFFs), API layers, and mobile-adjacent platform tooling that supports performant, real-time user experiences.

You thrive in a fast-paced, product-driven environment where your hands-on expertise, architectural thinking, and collaborative mindset make an impact. You write scalable, maintainable code across client and server layers, contribute to technical direction, and help level up those around you.

You’ll join the Fanatics Casino team, which owns the full iCasino experience across Fanatics platforms, including our standalone Casino App, iCasino within the Fanatics SportsBook & Casino App, and our Casino Desktop website. Our mission is to build the top online casino in the U.S., with an emphasis on fun, dynamic, and entertainment-first products that resonate with our most valuable customer segment: Spinners.

Our mobile stack is powered by Kotlin, Jetpack Compose, Compose Multiplatform, SwiftUI, and Kotlin Multiplatform Mobile (KMM). Our backend systems leverage Kotlin/Java-based services and distributed system patterns to support scale, performance, and real-time interactions.

Responsibilities

• Develop, test, document, and deploy high-quality mobile software using Kotlin and Jetpack Compose.
• Contribute to backend services supporting mobile clients, including BFF patterns and mobile-optimised APIs.
• Design and implement scalable backend components using Kotlin or Java within distributed systems.
• Build and evolve UI and business logic using Compose and shared Kotlin code, aligning with our cross-platform strategy.
• Work on real-time communication patterns such as WebSockets, Server-Sent Events (SSE), or GraphQL where appropriate.
• Collaborate with backend and platform teams to design API gateways and mobile-facing services.
• Deliver features end-to-end, from functional requirements through implementation, testing, release, and iteration.
• Contribute to technical design discussions spanning client and server boundaries.
• Participate in our on-call rotation and help resolve production issues across both mobile and backend systems.
• Improve testability, reliability, observability, and documentation while executing on refactoring and tech debt reduction.
• Mentor junior engineers and contribute to shared libraries and platform standards.
• Contribute to sprint planning, estimation, and retrospective processes.
• Develop a strong understanding of the iCasino product and how backend design directly impacts mobile performance and experience.
   

Required Qualifications

• Minimum 5+ years of professional software development experience.
• Strong Kotlin (or Java) expertise with production experience.
• Hands-on experience building Android apps using Jetpack Compose.
• Experience contributing to backend services in distributed systems.
• Experience working with REST APIs and designing mobile-optimised backend integrations.
• Solid understanding of mobile architecture, app lifecycle, state management, and modern UI design principles.
• Strong understanding of distributed systems fundamentals (scalability, resilience, state management).
• Experience with real-time or event-driven systems (e.g., WebSockets, SSE, messaging systems, or GraphQL).
• Demonstrated ability to deliver high-quality, maintainable code across client and server layers.
• Strong debugging and problem-solving skills, especially in production environments.
  
   

Preferred Qualifications

• Experience building or maintaining Backends for Frontends (BFFs).
• Familiarity with API gateways and edge-layer concerns.
• Experience working with Content Management Systems (CMS) or tooling that supports dynamic mobile content.
• Experience with Compose Multiplatform and/or Kotlin Multiplatform Mobile (KMM).
• iOS development experience (Swift / SwiftUI).
• Experience in CI/CD environments (GitHub Actions, Bitrise, etc.).
• Understanding of observability practices (logging, crash reporting, performance monitoring).
• Exposure to high-growth or startup environments.
• Passion for mobile gaming, entertainment products, or real-time user experiences.
  
   

Not sure if you check every box?

If you're excited about this role, passionate about Kotlin across mobile and backend systems, and interested in building world-class entertainment experiences powered by modern distributed architectures — we encourage you to apply. We value strong engineers who can operate across layers and think holistically about user experience and system design.