Senior Mobile SDK Platform Engineer (Remote)

Unifonic, Inc.

United States

Remote

USD 150,000 - 210,000

Full time

14 days+

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Benefits offered by this job

Competitive salary and bonus

Unifonic share scheme

30 holiday days after first year

Worldwide remote work option

Job summary

Unifonic, Inc. is seeking an experienced Mobile Platform Engineer to own the SDK platform end-to-end. You’ll shape the public API, ensure platform‑wise consistency, and drive a robust release and testing process across iOS, Android, and web environments.

You will work on Rust cores and shell executors, translate OS lifecycle into SDK behavior, and maintain a high bar for documentation, tooling, and partner integration. A strong focus on AI‑assisted development and code review is essential.

Qualifications

7+ years of software engineering experience, including 2+ years working on a library, SDK, framework, or platform consumed by third‑party developers.
Strong experience with public API design and Semantic Versioning (SemVer), including managing deprecations without breaking existing customers.
Deep understanding of mobile platform lifecycles, including process death and restoration, background execution limits, push wake‑ups, extensions, and platform services.
Hands‑on experience with native build systems and packaging, including publishing to a package registry and troubleshooting third‑party builds.
Experience with FFI and language interoperability, such as JNI/NDK on Android, C interoperability with Swift, or another production‑shipped language boundary.
Experience supporting third‑party integrators through documentation, technical support, troubleshooting, and analyzing symbolicated crash reports.
Strong testing mindset, using tests as a design tool rather than simply a validation step; experience with property‑based or mutation testing is a plus.
Excellent technical writing skills, with experience creating ADRs, changelogs, migration guides, and developer documentation.
Comfortable reviewing code across Android and iOS, with the ability to identify lifecycle, concurrency, and threading issues.
Strong experience with AI‑assisted development and coding agents, with the ability to thoroughly review, validate, and explain AI‑generated code before it reaches production.

Responsibilities

Designing the public API of the SDK on your primary platform and keep it idiomatic: async/AsyncSequence on iOS, suspend/Flow on Android, Promises and events on the web.
Writing the contract for each feature by hand: new event and command variants in the core, the public API shape, and the conformance vectors that every shell must pass.
Implementing features in the Rust core and the shell executors, with coding agents doing much of the typing and you owning every line that merges.
Translating OS lifecycle into SDK behavior: scene phases, process death, background limits, push wake-ups, connectivity changes, app extensions.
Building and keeping green the release pipeline: XCFramework, AAR, npm packages and sample apps, signed, with symbols, SBOM and privacy manifest.
Running the consumer test matrix: tiny storefront apps per configuration (minimum Xcode and AGP, R8 full mode, arm64-only ABI filters, React Native new architecture, Expo prebuild, Vite, webpack, Next.js).
Handling merchant tickets on rotation: triage by layer, replay diagnostics bundles, fix with a new vector or platform test, ship a patch release.
Shipping platform-specific add-ons beside the common SDK: rich push with product images, in-app campaign UI, Android Binder service, FCM forwarding, App Attest and Play Integrity.
Keeping the observability contract: structured logs with correlation ids, metrics callbacks, stable error codes, diagnostics() and selfCheck().
Tracking annual OS, Xcode, AGP and React Native changes and land them before merchants hit them.
Writing what you decide: ADRs, changelogs, migration notes and integration docs that a person or a coding agent can follow to a first tracked event in under 30 minutes.