Senior Frontend Software Engineer, AI UX

About the role

You will join the AI & Knowledge team at PEBL to shape the future of AI-driven user experiences, taking ownership of the end-to-end creation of Alfie, our conversational AI assistant. This position centers on frontend and product engineering, where you will architect and build direct user experiences that define how humans interact with software intelligence. You are expected to advocate for superior user experience in AI products, pushing boundaries beyond basic implementations to deliver delightful and intuitive interfaces. The role involves exploring and prototyping novel interaction models for conversational and generative AI as underlying technologies evolve, ensuring PEBL remains at the forefront of innovation. You will contribute directly to the evolution of software interaction at the company, working on sophisticated conversational and agentic UX that sets industry standards. This position requires a full-stack perspective, where you will develop and maintain both frontend and backend components, establishing clean contracts and APIs for complex agentic workflows. You will set high standards for code quality, mentor junior engineers, and promote a culture of continuous learning within the AI & Knowledge team.

Key facts

What you'll do

• Design and implement full-stack features for our AI assistant, with a primary focus on the frontend and user experience, ensuring pixel-perfect execution and seamless interaction flows.
• Apply practical knowledge of LLM-based and agentic systems to influence both AI behavior and its presentation in the UI, bridging the gap between model capabilities and user expectations.
• Advocate for superior user experience in AI products, challenging assumptions and driving decisions that prioritize intuitive and accessible interfaces over minimal viable outputs.
• Explore and prototype new interaction models for conversational and generative AI as underlying technologies advance, conducting experiments to validate novel concepts.
• Contribute to the evolution of software interaction at PEBL, working on novel conversational and agentic UX that redefines user engagement with digital assistants.
• Develop and maintain both frontend and backend components, ensuring clean contracts and APIs for agentic workflows that are robust, scalable, and maintainable.
• Set high standards for code quality, mentor junior engineers, and promote continuous learning through code reviews, pair programming, and knowledge-sharing sessions.
• Participate in technical discussions, design reviews, and code reviews to uphold engineering excellence and ensure architectural consistency across the product.
• Diagnose and resolve production issues across the stack, including AI-specific problems like poor model output or latency, using observability tools and debugging techniques.
• Collaborate with product managers, designers, and researchers to translate abstract ideas into concrete user-facing features that deliver tangible value.
• Implement responsive and accessible interfaces that work across a variety of devices and screen sizes, maintaining a consistent design system.
• Optimize application performance for speed and scalability, focusing on reducing latency in AI-driven interactions and improving perceived responsiveness.
• Integrate with third-party APIs and services, managing authentication, rate limiting, and error handling to ensure reliable system behavior.
• Write and maintain comprehensive documentation for components, APIs, and user flows, enabling other engineers to onboard and contribute efficiently.

Requirements

• 8+ years of professional software engineering experience, with a strong preference and demonstrated skill in frontend/UX, ensuring a deep understanding of user-centered design principles.
• 1+ years of hands-on experience building products powered by LLMs or agents, focusing on agent reasoning and tool usage, with a portfolio of shipped features.
• Experience creating interfaces for AI-driven products, including conversational UIs and dynamic interfaces that adapt to model behavior, showcasing versatility in design patterns.
• Solid grasp of LLM design principles, prompt engineering, and observability for agentic systems, allowing you to make informed technical trade-offs.
• Strong proficiency in modern frontend technologies (React/TypeScript) and understanding of backend integration with APIs and streaming data, enabling full-stack collaboration.
• Proven track record of developing sophisticated products beyond standard CRUD applications, showcasing craft and distinctive user experiences that stand out in the market.
• Willingness to work across the full stack (backend, infrastructure) as needed, demonstrating ownership of the entire feature lifecycle from conception to deployment.
• A lean development mindset, prioritizing customer value, efficiency, and rapid iteration, ensuring that every engineering decision aligns with product goals.
• Enthusiasm for working in a rapidly evolving field, eager to discover new patterns for AI-driven UX and continuously experiment with emerging techniques.
• Ability to communicate effectively with both technical and non-technical stakeholders, translating complex concepts into clear and actionable insights.
• Commitment to writing clean, testable, and maintainable code, with a focus on modularity and reusability across the codebase.
• Willingness to adhere to company standards and best practices, ensuring that all contributions align with the overall vision and architecture.

Nice to have

• Experience with generative/dynamic UI techniques, such as real-time data visualization and adaptive interfaces that respond to user input.

Skills & tools

• TypeScript
• React
• LLM-based systems
• Agentic systems
• Prompt engineering
• API design
• Real-time/streaming data

Practical notes

• This role requires in-office collaboration Monday through Wednesday at our Palo Alto, CA office.
• Benefits include flexible time off, parental leave, health and dental insurance, and retirement savings with an employee incentive plan.