Senior Software Engineer, Supercell ID (Client SDK)

We are looking for a Senior Software Engineer to join the Supercell ID product team. Supercell ID connects hundreds of millions of players to Supercell’s ecosystem. We build the account and identity system that connects our games and web services into a cohesive player experience, covering everything from registration and login to account safety, compliance and identity. This is a hands-on product engineering role with significant responsibility for the success of our initiatives. You’ll build player-facing features in the client SDK embedded in every Supercell game, while helping decide what we should build and how it should work. You’ll collaborate directly with game teams and other teams across Supercell. Our client codebase is currently a mix of C++, Flutter and web technologies. Supercell's games are built in C++, and much of the integration between the games and the SDK you'd be working on is native code. Player-facing experiences and flows are currently mostly built with Flutter, while we're moving toward a future where most of our UX is delivered through webviews. You'll work with the codebase as it exists today while helping us make that transition. We don't expect you to have prior experience with every technology we use. What matters is that you can work across native and web boundaries, learn unfamiliar parts of the stack and choose solutions that work well for players and game teams. You Might Be The Right Fit if You think like a product owner as much as an engineer. You care whether what we build is understandable, useful and successful. You form opinions from data, feedback and firsthand experience, and advocate for changes when you think we can do better. You have a strong sense of ownership. Getting a PR merged is only the beginning: you follow your work through testing and release and care about whether it actually solved the problem. When something isn’t working for players or game teams, you’re inclined to do something about it even if nobody has explicitly asked you to. You’re comfortable starting with a problem rather than a specification. You work with others to understand what actually needs solving, challenge assumptions when needed, and turn ambiguity into incremental solutions that deliver value. You collaborate directly and naturally across disciplines. You seek out the people closest to a problem rather than working through layers of intermediaries. You care about engineering quality in a product used at enormous scale: testability, backward compatibility, maintainability and avoiding surprises for the teams and players who depend on your work. You’ve taken meaningful ownership of cross-team projects and are comfortable working with both engineering and non-engineering stakeholders. What You'll Be Doing Architect, build and ship the Supercell ID client SDK, shared code that runs inside every Supercell game across iOS, Android and other platforms. Build player-facing account experiences embedded in our games, balancing usability, account safety and the constraints of individual games and platforms. Lead implementation efforts: Collaborate with product managers, designers, analysts, game teams, legal teams, and more, take a software project from idea to market and into operations. Help shape what we build, not just how we build it. Use data, feedback and firsthand experience to identify problems and turn them into product improvements. Work directly with game teams to make integrations smooth, keep the SDK footprint small and understand the real-world problems they encounter. Take part in the team’s client support rotation, staying close to integration issues and production problems affecting game teams and players. What You Have Prior experience building consumer-facing mobile applications for iOS and/or Android using Swift, Kotlin, C++ or Flutter/Dart - or a mixture of those. You understand platform constraints and application lifecycles, and can diagnose performance and runtime issues. Willingness to learn the unfamiliar parts of our stack, and work on any part of the system. Comfort using modern development tools, including AI coding agents, as part of your everyday work. Would Be Nice if You Also Have Experience shipping web-based user experiences. Having experience embedding them in native applications would be particularly relevant. Experience building SDKs, libraries or other components used across multiple applications. Experience with routine backend development as part of end-to-end feature development. Where You'll Be You will work from our Helsinki Studio where most of your core stakeholders and wider team members will be located. We are more in office than remote but have flexibility to work from home when needed. ––– That's it about the role! Below, we've gathered some things we feel are important for you to know. Totally optional, but a highly recommended read. Once you're ready to apply, just send us your application through the form on the bottom of the page. –––