Block's Bitkey is looking to solve the problem of making Bitcoin self-custody safe and easy for everyone, bridging cryptography with simple, everyday experiences, and breaking the historical trade-off between security and usability in the market.
Requirements
- Proven experience shipping production Bitcoin software, or deep protocol expertise with a desire to build for customers, whether from a backend, custody, or mobile background.
- Baseline understanding of secure key management and recovery problems.
- Strong engineering fundamentals and comfort moving across stacks and languages (we use Rust and Kotlin, and can help you learn them if they’re new to you).
- Familiarity with applied cryptographic techniques in Bitcoin custody.
- Experience building SDKs, APIs, or libraries consumed by mobile apps.
- Contributions to open-source Bitcoin projects.
- Experience with security-sensitive or correctness-critical systems
Responsibilities
- Design, build, and maintain secure backend services and libraries that enable safe and usable Bitcoin self-custody.
- Create platform primitives and APIs that mobile apps and external clients can rely on.
- Work across boundaries — from cryptographic protocols, to custody flows, to integration with mobile experiences, with a bias toward pragmatic problem-solving.
- Collaborate closely with product managers, designers, and other engineers to deliver solutions that balance usability, availability, and security.
- Take end-to-end ownership of projects, from ideation through execution.
Other
- A deep interest in Bitcoin and conviction about the importance of self-custody.
- A track record of collaborating in cross-functional teams and contributing beyond just code.
- Curiosity, creativity, and a drive to innovate in service of real customer needs.
- Candidates may come from backend, platform, or even mobile backgrounds, but success in this role requires deep experience with Bitcoin protocols applied in production and strong engineering fundamentals.
- You’ll join a mission-driven team that values curiosity, creativity, and collaboration.
