Senior Android Engineer, Bitkey

Proto is accelerating the world's transition to an open economy with products that increase access and independence for everyone. We're building Bitkey, a simple and safe self-custody bitcoin wallet that will put customers in control, as well as hardware and software that will help decentralize bitcoin mining and enable new and innovative use cases for bitcoin mining. We're developing these products in the open - you can read more about them at bitkey.build and mining.build. Within Proto, our Bitcoin Products team delivers the product and go-to-market strategy, software, firmware, and custom silicon needed to make Bitkey and our ambitious mining initiatives a reality. Come build the future of money with us!

The Role

Bitkey is a self-custody Bitcoin wallet designed to bring financial ownership to a global audience. We are a small, high-impact team within the Proto organization at Block, working in the open to advance the principles of Bitcoin—individual sovereignty, decentralization, and permissionless access to money.

We're looking for a Senior Android Engineer to help scale our Kotlin Multiplatform (KMP) architecture and deliver new product experiences that empower people to own and control their money. In this role, you'll bring deep mobile expertise—either in Android or KMP—and help shape the evolution of our multiplatform codebase and delivery pipeline. You'll collaborate across design, product, and backend teams to ship features end-to-end, from architecture to post-launch observability and iteration.

We are looking for an engineer who thrives on building trustworthy, user-first experiences—and who's excited about the technical challenges of delivering a product where security and reliability are critical, to people around the world.

You Will

• Work across disciplines to ship critical features across Android and iOS using Kotlin Multiplatform
• Join architecture and platform evolution discussions to improve the developer ergonomics of our mobile codebase, and to enhance its testability, performance, and security
• Mentor and collaborate with mobile engineers across the team to raise the bar on design, code quality, and system resilience
• Extend and improve our mobile CI/CD pipeline and build infrastructure, with a focus on reliability, automation, and developer experience

You Have

• 8+ years of experience in Android development
• Deep experience architecting Android applications at scale and/or strong experience with Kotlin Multiplatform in production
• Interest in contributing to the design and evolution of multi-platform codebases and development patterns
• Familiarity with modern Android build systems and tooling such as Gradle, CI/CD automation, performance tuning, and static analysis tools
• Experience collaborating with backend teams to design robust, scalable mobile APIs
• Passion for financial empowerment and an interest in Bitcoin, decentralized technologies, or digital identity
• Interest in exploring and applying AI tools to improve mobile development workflows and in helping define best practices for integrating them into our mobile engineering pipeline

Technologies We Use and Teach

• Kotlin & Kotlin Multiplatform
• Compose Multiplatform
• Swift
• SQLite / SQLDelight
• Rust

We're working to build a more inclusive economy where our customers have equal access to opportunity, and we strive to live by these same values in building our workplace. Block is an equal opportunity employer evaluating all employees and job applicants without regard to identity or any legally protected class. We will consider qualified applicants with arrest or conviction records for employment in accordance with state and local laws and “fair chance” ordinances.

We believe in being fair, and are committed to an inclusive interview experience, including providing reasonable accommodations to disabled applicants throughout the recruitment process. We encourage applicants to share any needed accommodations with their recruiter, who will treat these requests as confidentially as possible. Want to learn more about what we're doing to build a workplace that is fair and square? Check out our I+D page.

While there is no specific deadline to apply for this role, U.S. roles are typically open for an average of 55 days before being filled by a successful candidate. Please refer to the date listed at the top of this job page for when this role was first posted.