Software Development Engineer in Test

Hiya (Headquarters: Seattle / London / Budapest)

SDET QA Test Automation Mobile Testing iOS Android AI LLM AWS Node.js hybrid Seattle prompt engineering non-deterministic testing AI Engineer Mobile Engineer

Company: Hiya
Hiya makes your mobile calling experience smarter and more relevant. We partner with phone makers and telecom carriers to bring this innovation to over 500+ million global subscribers and growing. Our mission is to protect against spam and fraud, connect businesses with customers, and secure global telecommunications.

About the Position:
The Senior Software Engineer in Test is responsible for ensuring the quality of Hiya's mobile and AI-driven applications. In this role, you will lead end-to-end quality assurance efforts across our mobile app, integrated SDKs, backend services, and AI-powered features. Your responsibilities will include designing and implementing test strategies for mobile platforms and backend services, leading testing efforts across service layers, and conducting hands-on testing and validation of AI-driven features, including establishing baselines for non-deterministic testing. Our team develops iOS and Android applications, services on Node.js, and integrations with AWS-based products. AI underpins core mobile features, making testing, validation, and experimentation in an AI context essential.

What You’ll Do:
* Automate testing processes and scripts to verify and ship our flagship mobile applications.
* Design and execute experiments to assess the robustness and adaptability of AI models in real-world scenarios.
* Research and maintain tools and frameworks for evaluating AI model performance and prompt effectiveness.
* Collaborate with AI Engineers to ensure quality and functionality in non-deterministic systems.
* Mentor junior team members and contribute to the continuous improvement of testing processes.
* Work closely with product managers, designers, and cross-functional teams to balance innovation with steady delivery.
* Develop comprehensive QA plans for mobile features (e.g., AI call screening, real-time scam detection, on-device transcription) and backend services.
* Own and drive Hiya’s QA processes while fostering a culture of feedback and collaboration.

What You’ll Need to Succeed:
* Hands-on experience automating mobile application testing.
* Familiarity with AI-driven features, prompt engineering, and the non-deterministic nature of LLM output.
* A solid understanding of modern cloud service deployment and management.
* Experience working in a startup (<500 employees) within the last five years or a strong ability to thrive in a fast-paced, high-ambiguity environment.
* Embody Hiya’s key values: Serving our customers, Doing rather than observing, Improving ourselves and our business, Owning and holding ourselves accountable for success and Leading by showing up with a POV, engaging in discussion, listening respectfully to others opinions and committing to decisions.

You will have a fast start if you have experience:
* Shipping code which automates mobile applications with consistency
* Developing test plans, troubleshooting ambiguous bug reports, and refining repro steps.
* Testing and ensuring quality of AI-supported features
* Skills in verifying non-deterministic behaviors in different contexts
* Writing and sharing scripts to facilitate creating and execution of customized test scenarios
* Mobile app development for iOS and Android.
* Software development in telephony and VoIP.

Ideal Candidate:
An experienced SDET with strong mobile automation skills and familiarity with testing AI/LLM features. Comfortable working in a startup environment and collaborating across teams.