(Contract) Software Engineer - Android / SDK (Kotlin, Kotlin Multiplatform, C++)

Type: Contract, per-project.
Location: Remote - alignment with North America is preferred (ideally Pacific Time, acceptable PT-ET).
Availability: Contractor (40 hours per week)

We’re looking for a highly capable Software Engineer to join our Powered team and help build the core libraries behind every Speedtest client, as well as the SDKs used by device manufacturers and third-party application developers worldwide.

You’ll work on low-level networking features, platform-specific implementations and cross-platform SDKs that directly impact how millions of users measure and understand their Internet performance.

What you’ll do

• Design and build core SDK and library features used by Speedtest clients and third-party partners

• Develop network testing functionality using Kotlin and Kotlin Multiplatform

• Build and maintain performance-critical components using C++

• Maintain and support legacy SDK products built in Java

• Design clean, well-structured and easy-to-use APIs for both SDK and application use

• Work close to Android platforms, device hardware and, in some cases, embedded environments

• Ensure high levels of reliability, flexibility, portability and code reuse

• Implement analytics and telemetry to monitor performance and behavior in production

• Write unit, integration, load and stress tests

• Debug and troubleshoot complex, multi-layer and multi-platform issues

• Collaborate on architecture and technical decisions across SDK, frontend, backend and distributed server teams

• Contribute to documentation, developer support and long-term maintenance of SDKs

• Participate in code reviews and continuous improvement of engineering practices

What we’re looking for

• 5+ years of professional software development experience

• 3+ years of professional Android development experience

• Strong proficiency in Kotlin and Java

• Solid knowledge of data structures, algorithms and design patterns

• Hands-on experience building and maintaining SDKs or reusable libraries

• Strong understanding of Android Framework and Android SDK development

• Experience with threading, concurrency and performance optimization on Android

• Experience with networking frameworks such as OkHttp and TCP sockets

• Strong understanding of networking fundamentals (IP, TCP/UDP, HTTP/S, WebSockets)

• Experience designing cross-platform libraries (Kotlin Multiplatform or similar)

• Experience writing unit, integration, load and stress tests

• Strong debugging and troubleshooting skills

• Experience working with Git-based workflows (branches, pull requests, code reviews)

• Experience with CI/CD pipelines

• Ability to ramp up quickly on new projects and complex codebases

• Strong communication and collaboration skills in distributed teams

• High level of ownership, autonomy and time-management skills

Nice to have

• Experience with C++

• Experience with Swift

• Experience contributing to open-source projects

• Previous experience working with embedded or hardware-adjacent environments

(*) SOUTHWORKS only hires individuals from countries that are not blocked or sanctioned by the United States, including those identified on the United States Office of Foreign Asset Control (OFAC).