We are looking for a Senior Mobile Engineer to maintain and optimize native iOS and Android voice and messaging applications, with a strong focus on Swift (70%) and Kotlin (30%), while leading Proof of Concept work to evaluate migration toward React Native. You will implement and optimize Real-Time Communication capabilities including WebRTC, SIP, and VoIP push notifications, solve complex voice, network latency, and socket reliability challenges, and collaborate directly with client stakeholders on mobile architecture and feature decisions.

What you will do

Maintain, enhance, and optimize existing native Android (Kotlin) and iOS (Swift) mobile applications.
Design and build Proofs of Concept (PoCs) to evaluate and execute the transition of native apps to React Native.
Implement and optimize Real-Time Communication (RTC) capabilities, including WebRTC, SIP, and in-app chat features.
Solve complex mobile voice issues related to VoIP/voice-enabled push notifications, socket connections, and network latency.
Collaborate directly with key client stakeholders to refine mobile architecture and feature specifications.
Conduct code reviews, establish best practices for mobile stability, and drive continuous performance improvements.
Operate in an Agile delivery workflow with regular sprint planning and technical iterations.

Must haves

3+ years of hands-on professional mobile development experience across both iOS and Android platforms.
Strong, direct experience writing native mobile applications in Swift (iOS) and Kotlin (Android). (Role will be 70% oriented in Swift and 30% oriented in Kotlin.)
Exposure or knowledge of React Native.
Solid domain experience with Real-Time Communication (RTC), specifically WebRTC, SIP, or VoIP architecture.
Proven experience implementing voice-enabled push notifications (e.g., PushKit, CXProvider, VoIP background modes) and handling network latency in voice/chat apps.
Strong technical problem-solving ability with a senior-level mindset for app stability and connection reliability.
Based in LATAM or Ukraine with at least 4 hours of EST time zone overlap.
Excellent written and spoken English communication skills for client-facing collaboration.

Nice to haves

Direct experience migrating native mobile applications (Swift/Kotlin) to React Native.
Deep understanding of socket connections, audio packet management, and mobile bandwidth optimization.
Background in developing specialized VoIP or real-time communication consumer applications.
Experience working in high-growth startup or dedicated remote agency environments.

Perks

Growth without limits: build your skills through mentorship, internal TechTalks, challenging projects, and a dedicated annual learning budget
Competitive compensation: get recognition that reflects your skills and impact, with regular performance and compensation reviews
Flexibility: work 100% remotely with flexible hours that support focus, autonomy, and a healthy work rhythm
Meaningful, modern projects: build impactful products using modern technologies alongside global teams and leading brands
Collaborative culture: join a supportive environment with zero micromanagement where ideas are welcomed and contributions are recognized
Well-being & support: access local well-being programs and people-focused support tailored to your location