Staff Software Engineer (Mobile), Proto

  • Full-time

Company Description

Block is one company built from many blocks, all united by the same purpose of economic empowerment. The blocks that form our foundational teams — People, Finance, Counsel, Hardware, Information Security, Platform Infrastructure Engineering, and more — provide support and guidance at the corporate level. They work across business groups and around the globe, spanning time zones and disciplines to develop inclusive People policies, forecast finances, give legal counsel, safeguard systems, nurture new initiatives, and more. Every challenge creates possibilities, and we need different perspectives to see them all. Bring yours to Block.

Job Description

Bitkey sits within the Proto organization. Proto's purpose is to accelerate the world’s transition to a more open economy by making products that increase access and independence for everyone. The first two initiatives we’ve identified that represent the biggest impact to this purpose are in the Bitcoin space with Bitcoin mining and Bitkey, a self custody Bitcoin wallet. While we’re starting there, we don’t believe the need for tools to increase one’s independence is limited to bitcoin or the financial space. One principle across everything we do in Proto is open development – show and tell. We develop products in the open, you can read more about them at and

We are growing our small cross-discipline engineering team and are looking for a mobile engineer who has experience architecting Kotlin Multiplatform solutions or deep experience architecting Kotlin-based Android solutions at scale with a strong interest in diving deep into Kotlin Multiplatform. We have blurred the lines of a traditional Android and iOS team by focusing on the right, single solution across multiple platforms. We’re looking for someone to help our team of passionate mobile engineers shape our multiplatform story in a scalable, sustainable, and secure way.

This role will also include deep feature development work in the Bitkey self-custody wallet with our existing team of mobile and server engineers. After all, the best way to help shape our architecture is to build in it!


You will:

  • Ship critical features in a non-custodial, hardware-enabled bitcoin wallet to a global audience

  • Collaborate with and help lead an experienced group of mobile engineers to evolve our multi-platform mobile system architecture, advance our testing capabilities and performance, and help iterate on and improve our mobile CI infrastructure 

  • Improve our mobile release pipeline by increasing automation and improving reliability 

  • Work closely with designers and product managers to build user experiences expanding the offerings of Bitkey 

  • Work with a small team of engineers across our Mobile Application (KMP, Kotlin, Swift) and Rust backend on a team responsible for features from ideation through long-term maintenance


You have:

  • 12+ years of engineering experience with a significant focus on mobile development 

  • Experience architecting Android mobile applications with some experience or interest in Kotlin Multiplatform

  • Experience designing and building APIs between mobile applications and backend services

  • Knowledge of build tooling such as Gradle. 

  • Experience with building new or iterating on existing mobile CI infrastructure

  • Experience working with small cross-functional teams. Bonus points for working on 0->1 features

  • Interest in the opportunities and challenges that come with building a global-first product from the ground up

  • Interest in Bitcoin and expanding financial access to everyone

Technologies We Use and Teach

  • Mobile Application

    • Kotlin

    • Kotlin Multiplatform

    • Swift

    • SQLite

  • Backend Services

    • AWS

    • DynamoDB

    • Rust

  • Other

    • Github

    • Datadog

Additional Information

Block takes a market-based approach to pay, and pay may vary depending on your location. U.S. locations are categorized into one of four zones based on a cost of labor index for that geographic area. The successful candidate’s starting pay will be determined based on job-related skills, experience, qualifications, work location, and market conditions. These ranges may be modified in the future.

Zone A: USD $239,600 - USD $359,400
Zone B: USD $239,600 - USD $359,400
Zone C: USD $239,600 - USD $359,400
Zone D: USD $239,600 - USD $359,400

To find a location’s zone designation, please refer to this resource. If a location of interest is not listed, please speak with a recruiter for additional information. 

Full-time employee benefits include the following:

  • Healthcare coverage (Medical, Vision and Dental insurance)
  • Health Savings Account and Flexible Spending Account
  • Retirement Plans including company match 
  • Employee Stock Purchase Program
  • Wellness programs, including access to mental health, 1:1 financial planners, and a monthly wellness allowance 
  • Paid parental and caregiving leave
  • Paid time off (including 12 paid holidays)
  • Paid sick leave (1 hour per 26 hours worked (max 80 hours per calendar year to the extent legally permissible) for non-exempt employees and covered by our Flexible Time Off policy for exempt employees) 
  • Learning and Development resources
  • Paid Life insurance, AD&D, and disability benefits 

These benefits are further detailed in Block's policies. This role is also eligible to participate in Block's equity plan subject to the terms of the applicable plans and policies, and may be eligible for a sign-on bonus. Sales roles may be eligible to participate in a commission plan subject to the terms of the applicable plans and policies. Pay and benefits are subject to change at any time, consistent with the terms of any applicable compensation or benefit plans.

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 a proud equal opportunity employer. We work hard to evaluate all employees and job applicants consistently, without regard to race, color, religion, gender, national origin, age, disability, veteran status, pregnancy, gender expression or identity, sexual orientation, citizenship, or any other legally protected class. 

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.

Additionally, we consider qualified applicants with criminal histories for employment on our team, assessing candidates in a manner consistent with the requirements of the San Francisco Fair Chance Ordinance.


Block, Inc. (NYSE: SQ) is a global technology company with a focus on financial services. Made up of Square, Cash App, Spiral, TIDAL, and TBD, we build tools to help more people access the economy. Square helps sellers run and grow their businesses with its integrated ecosystem of commerce solutions, business software, and banking services. With Cash App, anyone can easily send, spend, or invest their money in stocks or Bitcoin. Spiral (formerly Square Crypto) builds and funds free, open-source Bitcoin projects. Artists use TIDAL to help them succeed as entrepreneurs and connect more deeply with fans. TBD is building an open developer platform to make it easier to access Bitcoin and other blockchain technologies without having to go through an institution.

While there is no specific deadline to apply for this role, on average, U.S. open roles are posted for 70 days before being filled by a successful candidate.

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