Principal Engineer Frontend

Pennymac•Westlake Village, CA

12d•$90,000 - $150,000•Onsite

About The Position

As a Principal Frontend Engineer on the AI Platform Services team, you will be the architect of the platform's "face" and the guardian of the user experience. While the backend team builds the "brain" (RAG pipelines and autonomous agents), you will build the "Collaborative Canvas"—the interface where human ingenuity meets artificial intelligence. You will not just be building standard dashboards; you will be engineering complex, AI-native interfaces that rival commercial tools like Cursor and Linear. You will solve unique challenges in Generative UI, real-time state synchronization, and browser-based code editing. You will define how our engineers interact with autonomous agents, moving beyond simple "chatbots" to build a deeply integrated, multi-modal workspace that feels like a natural extension of the person's mind. This role requires a unique blend of elite frontend engineering, a deep understanding of developer tooling (IDEs, CI/CD interfaces), and a visionary approach to Human-Computer Interaction (HCI) in the age of AI. Why Join Pennymac? Chart Pennymac’s AI Course: This is a greenfield opportunity to join a foundational team and build a transformative platform from the ground up, with the stability and resources of an industry leader. Define the AI Interface: This is an opportunity to invent new UI patterns for "Agentic Workflows." You will move beyond static forms to build interfaces that generate themselves based on user intent and AI context. High-Impact & Visibility: Nexus is a top-priority strategic initiative. Your work will be the primary touchpoint for senior leadership and hundreds of engineers, directly impacting the "Idea-to-Production" velocity of the entire organization. Solve Unique Problems: You will tackle cutting-edge challenges in Collaborative Editing (CRDTs), Streaming UI, and Visualizing Complex Agent Reasoning—problems that sit at the bleeding edge of modern web development. Competitive Compensation: We offer a competitive salary, bonus, and benefits package, including comprehensive health/dental/vision plans, 401(k) matching, and more. Career Growth: We are committed to the growth of our team members and provide opportunities for continuous learning, professional development, and career advancement within a leading FinTech company.

Requirements

Bachelor’s Degree in Computer Science, HCI, or related engineering disciplines, or equivalent professional experience.
Elite Expertise in React & TypeScript: A proven track record (8+ years) of building complex, data-heavy Single Page Applications (SPAs). Deep mastery of React internals, hooks, context, and performance optimization.
Next.js & Server Components: Experience with modern Next.js architectures (App Router), specifically leveraging Server Components and streaming for progressive UI rendering.
Real-Time Collaboration Experience: Hands-on experience building multi-user, real-time applications using WebSockets, SSE, or libraries like Yjs, Automerge, or Liveblocks. You understand the complexities of state synchronization and conflict resolution in distributed systems.
"Generative UI" / AI Integration: Demonstrable experience integrating LLM APIs (OpenAI, Anthropic, AWS Bedrock) into frontend applications. Experience with "streaming" UI responses and handling unstructured data.
Data Visualization: Proficiency with visualization libraries (e.g., D3.js, Recharts, React Flow, or Mermaid.js) to render complex dependency graphs and architecture diagrams.
A "Startup Mentality": High ownership, collaborative spirit, and adaptability. You are comfortable shipping an MVP "Collaborative Canvas" one week and refactoring it for scale the next based on user feedback.

Nice To Haves

Experience with AI SDKs: Familiarity with the Vercel AI SDK, LangChain.js, or similar frameworks for managing agentic state in the frontend.
Design Systems: Experience building or maintaining enterprise-grade Design Systems (e.g., using Tailwind CSS, Radix UI, or Shadcn).
Backend Fluency: Ability to write Node.js/Edge Functions to support "Frontend-for-Backend" (BFF) patterns.
Knowledge of ASTs: Understanding of Abstract Syntax Trees (ASTs) for code analysis and manipulation within the browser.
FinTech/Mortgage Domain: Familiarity with the regulatory and compliance constraints of the financial industry (e.g., SOX, GLBA).

Responsibilities

Architect the Agentic Workspace: Design and build the core frontend architecture for the AI platform using React, TypeScript, and Next.js, ensuring sub-second performance even with heavy data visualization and real-time streams.
Build the "Collaborative Canvas": Engineer a real-time, multi-player workspace where AI agents and humans can co-author artifacts (User Stories, PRDs, Architecture Diagrams). Implement CRDTs (Conflict-Free Replicated Data Types) and WebSocket infrastructures to manage shared state seamlessly without data loss.
Master the "Generative UI": Develop a robust component registry and rendering engine that allows AI agents to dynamically generate interactive UI elements (charts, forms, checklists) on the fly, rather than just outputting text.
Visualize Intelligence: Create intuitive visualizations for the "Unified Context Library," allowing users to see why an AI agent made a decision, trace its sources (Jira, Confluence, GitLab), and inspect its reasoning graph via interactive diagrams.
Partner with the Backend: Collaborate closely with Principal Backend Engineers to define the API contracts (GraphQL, Streaming JSON, Server-Sent Events) that enable the frontend to consume complex agent outputs efficiently.
Developer Experience (DX) Leadership: Work directly with your "customers" (Pennymac engineers and product analysts) to understand their workflows. Translate their friction points into elegant UI solutions that reduce context switching.
Establish Frontend Standards: Take ownership of the frontend DevOps pipeline, testing strategy (E2E/Integration), and architectural standards. Evangelize "AI-Native" design patterns across the broader technology organization.

Benefits

Comprehensive Medical, Dental, and Vision
Paid Time Off Programs including vacation, holidays, illness, and parental leave
Wellness Programs, Employee Recognition Programs, and onsite gyms and cafe style dining (select locations)
Retirement benefits, life insurance, 401k match, and tuition reimbursement
Philanthropy Programs including matching gifts, volunteer grants, charitable grants and corporate sponsorships

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