Remote · worldwide, UTC+4 acceptedSalary not disclosedfull-timeVerified 1w agoHimalayas
Most people think of bot detection mostly as a web problem. But when attackers face heavily protected web APIs, they often move to the mobile app to see if it can be abused instead — or if the mobile APIs are easier to automate.
Responsibilities
At the same time, the SDK runs inside other companies’ production apps, often used by millions of users. It has to be fast, stable, and easy to integrate. It cannot break builds or introduce noticeable performance overhead. It has to behave correctly across thousands of device models, OS versions, and application environments.
Building software under these constraints requires a different mindset than building a typical mobile application.
Castle is a small, profitable team building a real-time trust layer for modern platforms. Our mobile SDKs are a core part of that system. They collect signals used for device fingerprinting, behavioral analysis, and bot detection, and they must do so reliably at scale.
You will work on the Kotlin and Swift codebases, evolve the SDK architecture, design APIs used by thousands of developers, and ensure our mobile instrumentation remains reliable as the mobile ecosystem evolves.
Designing and improving the architecture of our iOS and Android SDKs
Building reliable signal collection mechanisms across device models and OS versions
Designing APIs and developer experience for third-party integrations
Managing build systems, versioning, CI/CD pipelines, and artifact publishing
You have strong experience with Kotlin and Swift (and ideally some C++). You understand mobile dependency management, build systems, and release workflows. You have worked with Gradle, CocoaPods, Swift Package Manager, or similar tooling.
You care about performance, stability, and developer experience. You know that an SDK failing inside someone else’s production app is very different from a bug in your own codebase. Maybe you’ve already experienced what it feels like to introduce a critical bug in software running on millions of devices — and you want to build the tooling and processes that allow fast iteration without sacrificing safety.
