As a Senior Full Stack Developer on the Personalization Platform team, you will design and build the web applications, tools, and backend services that empower data scientists, ML engineers, and product partners to develop, deploy, and monitor large-scale personalization systems at PayPal. You will own end-to-end development of high-quality user interfaces and scalable backend services that support experimentation, feature management, model configuration, insights dashboards, and real-time personalization workflows. In this role, you will combine strong engineering fundamentals with a product-driven mindset to create intuitive, performant, and reliable tools that accelerate the machine learning lifecycle. You will collaborate closely with cross-functional teams to translate complex personalization and ML requirements into robust system designs and seamless user experiences. Your work will involve integrating backend services with feature stores, streaming systems, model registries, and cloud infrastructure, while ensuring code quality, security, testing, and observability across the full stack. You will contribute to architectural decision-making, uphold engineering best practices, identify and resolve performance bottlenecks, and advocate for user-centered design principles. Ultimately, you will help build the platforms and interfaces that power personalization at scale and enable teams across PayPal to experiment, innovate, and deliver impactful ML-driven experiences.

Essential Responsibilities:

• Delivers complete solutions spanning all phases of the Software Development Lifecycle (SDLC) (design, implementation, testing, delivery and operations), based on definitions from more senior roles.
• Advises immediate management on project-level issues
• Guides junior engineers
• Operates with little day-to-day supervision, making technical decisions based on knowledge of internal conventions and industry best practices
• Applies knowledge of technical best practices in making decisions

Expected Qualifications:

• 3+ years relevant experience and a Bachelor’s degree OR Any equivalent combination of education and experience.

Additional Qualifications

• Strong proficiency in frontend technologies such as React, TypeScript, JavaScript, Redux, or modern UI frameworks. 

• Experience building robust backend services using Java, Node.js, Python, or Go. 

• Strong understanding of REST APIs, microservices, and distributed systems. 

• Experience integrating with cloud environments (GCP, AWS, Azure) and containerized services (Docker, Kubernetes). 

• Familiarity with relational and NoSQL databases, caching systems, and data modeling principles. 

• Solid understanding of CI/CD, automated testing, observability, and secure software development practices. 

• Excellent communication skills, with the ability to translate user needs into technical solutions. 

Preferred Qualifications

• Experience developing tools that support ML workflows (feature management, model monitoring, dashboards, experimentation tooling). 

• Familiarity with data streaming frameworks (Kafka, Flink) or real-time data processing pipelines. 

• Experience working with ML model metadata, feature stores, or model registries. 

• Understanding of A/B testing methodologies and experimentation dashboards.

• Background building internal developer tools or platform engineering products.